document.write( "Question 475893: Solve the system\r
\n" ); document.write( "\n" ); document.write( "2/3x-2/5y=2
\n" ); document.write( "0.03x+0.04y=0.67
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Algebra.Com's Answer #326331 by MathLover1(20855)\"\" \"About 
You can put this solution on YOUR website!
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Solved by pluggable solver: Solving a linear system of equations by subsitution

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\n" ); document.write( " \"%282%2F3%29%2Ax%2B%28-2%2F5%29%2Ay=2\" Start with the first equation
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\n" ); document.write( " \"15%28%282%2F3%29%2Ax%2B%28-2%2F5%29%2Ay%29=%2815%29%2A%282%29\" Multiply both sides by the LCD 15
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\n" ); document.write( " \"10%2Ax%2B-6%2Ay=30\"Distribute and simplify
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\n" ); document.write( " \"%283%2F100%29%2Ax%2B%284%2F100%29%2Ay=67%2F100\" Start with the second equation
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\n" ); document.write( " \"100%28%283%2F100%29%2Ax%2B%284%2F100%29%2Ay%29=%28100%29%2A%2867%2F100%29\" Multiply both sides by the LCD 100
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\n" ); document.write( " \"3%2Ax%2B4%2Ay=67\" Distribute and simplify
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\n" ); document.write( " Lets start with the given system of linear equations
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\n" ); document.write( " \"10%2Ax-6%2Ay=30\"
\n" ); document.write( " \"3%2Ax%2B4%2Ay=67\"
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\n" ); document.write( " Now in order to solve this system by using substitution, we need to solve (or isolate) one variable. I'm going to choose y.
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\n" ); document.write( " Solve for y for the first equation
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\n" ); document.write( " \"-6%2Ay=30-10%2Ax\"Subtract \"10%2Ax\" from both sides
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\n" ); document.write( " \"y=%2830-10%2Ax%29%2F-6\" Divide both sides by -6.
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\n" ); document.write( " Which breaks down and reduces to
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\n" ); document.write( " \"y=-5%2B%285%2F3%29%2Ax\" Now we've fully isolated y
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\n" ); document.write( " Since y equals \"-5%2B%285%2F3%29%2Ax\" we can substitute the expression \"-5%2B%285%2F3%29%2Ax\" into y of the 2nd equation. This will eliminate y so we can solve for x.
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\n" ); document.write( " \"3%2Ax%2B4%2Ahighlight%28%28-5%2B%285%2F3%29%2Ax%29%29=67\" Replace y with \"-5%2B%285%2F3%29%2Ax\". Since this eliminates y, we can now solve for x.
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\n" ); document.write( " \"3%2Ax%2B4%2A%28-5%29%2B4%285%2F3%29x=67\" Distribute 4 to \"-5%2B%285%2F3%29%2Ax\"
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\n" ); document.write( " \"3%2Ax-20%2B%2820%2F3%29%2Ax=67\" Multiply
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\n" ); document.write( " \"3%2Ax-20%2B%2820%2F3%29%2Ax=67\" Reduce any fractions
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\n" ); document.write( " \"3%2Ax%2B%2820%2F3%29%2Ax=67%2B20\"Add \"20\" to both sides
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\n" ); document.write( " \"3%2Ax%2B%2820%2F3%29%2Ax=87\" Combine the terms on the right side
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\n" ); document.write( " \"%289%2F3%29%2Ax%2B%2820%2F3%29x=87\" Make 3 into a fraction with a denominator of 3
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\n" ); document.write( " \"%2829%2F3%29%2Ax=87\" Now combine the terms on the left side.
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\n" ); document.write( " \"cross%28%283%2F29%29%2829%2F3%29%29x=%2887%2F1%29%283%2F29%29\" Multiply both sides by \"3%2F29\". This will cancel out \"29%2F3\" and isolate x
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\n" ); document.write( " So when we multiply \"87%2F1\" and \"3%2F29\" (and simplify) we get
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\n" ); document.write( " \"x=9\" <---------------------------------One answer
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\n" ); document.write( " Now that we know that \"x=9\", lets substitute that in for x to solve for y
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\n" ); document.write( " \"3%289%29%2B4%2Ay=67\" Plug in \"x=9\" into the 2nd equation
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\n" ); document.write( " \"27%2B4%2Ay=67\" Multiply
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\n" ); document.write( " \"4%2Ay=67-27\"Subtract \"27\" from both sides
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\n" ); document.write( " \"4%2Ay=40\" Combine the terms on the right side
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\n" ); document.write( " \"cross%28%281%2F4%29%284%29%29%2Ay=%2840%2F1%29%281%2F4%29\" Multiply both sides by \"1%2F4\". This will cancel out 4 on the left side.
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\n" ); document.write( " \"y=40%2F4\" Multiply the terms on the right side
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\n" ); document.write( " \"y=10\" Reduce
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\n" ); document.write( " So this is the other answer
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\n" ); document.write( " \"y=10\"<---------------------------------Other answer
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\n" ); document.write( " So our solution is
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\n" ); document.write( " \"x=9\" and \"y=10\"
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\n" ); document.write( " which can also look like
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\n" ); document.write( " (\"9\",\"10\")
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\n" ); document.write( " Notice if we graph the equations (if you need help with graphing, check out this solver)
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\n" ); document.write( " \"10%2Ax-6%2Ay=30\"
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\n" ); document.write( " we get
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\n" ); document.write( " graph of \"10%2Ax-6%2Ay=30\" (red) and \"3%2Ax%2B4%2Ay=67\" (green) (hint: you may have to solve for y to graph these) intersecting at the blue circle.
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\n" ); document.write( " and we can see that the two equations intersect at (\"9\",\"10\"). This verifies our answer.
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\n" ); document.write( " Plug in (\"9\",\"10\") into the system of equations
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\n" ); document.write( " Let \"x=9\" and \"y=10\". Now plug those values into the equation \"10%2Ax-6%2Ay=30\"
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\n" ); document.write( " \"10%2A%289%29-6%2A%2810%29=30\" Plug in \"x=9\" and \"y=10\"
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\n" ); document.write( " \"90-60=30\" Multiply
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\n" ); document.write( " \"30=30\" Add
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\n" ); document.write( " \"30=30\" Reduce. Since this equation is true the solution works.
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\n" ); document.write( " So the solution (\"9\",\"10\") satisfies \"10%2Ax-6%2Ay=30\"
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\n" ); document.write( " Let \"x=9\" and \"y=10\". Now plug those values into the equation \"3%2Ax%2B4%2Ay=67\"
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\n" ); document.write( " \"3%2A%289%29%2B4%2A%2810%29=67\" Plug in \"x=9\" and \"y=10\"
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\n" ); document.write( " \"27%2B40=67\" Multiply
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\n" ); document.write( " \"67=67\" Add
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\n" ); document.write( " \"67=67\" Reduce. Since this equation is true the solution works.
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\n" ); document.write( " So the solution (\"9\",\"10\") satisfies \"3%2Ax%2B4%2Ay=67\"
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\n" ); document.write( "
\n" ); document.write( " Since the solution (\"9\",\"10\") satisfies the system of equations
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\n" ); document.write( " \"10%2Ax-6%2Ay=30\"
\n" ); document.write( " \"3%2Ax%2B4%2Ay=67\"
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\n" ); document.write( " this verifies our answer.
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\n" ); document.write( "\n" ); document.write( "or\r
\n" ); document.write( "\n" ); document.write( "\"2%2F3x-2%2F5y=2\"\r
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\n" ); document.write( "\n" ); document.write( "plug in the solution (9,10)\r
\n" ); document.write( "\n" ); document.write( "\"%282%2F3%299-%282%2F5%2910=2\"\r
\n" ); document.write( "\n" ); document.write( "\"%282%2Fcross%283%29%29cross%289%293-%282%2Fcross%285%29%29cross%2810%292=2\"\r
\n" ); document.write( "\n" ); document.write( "\"2%2A3-2%2A2=2\"\r
\n" ); document.write( "\n" ); document.write( "\"6-4=2\"\r
\n" ); document.write( "\n" ); document.write( "\"2=2\"\r
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\n" ); document.write( "\n" ); document.write( "\"0.03x%2B0.04y=0.67\"\r
\n" ); document.write( "\n" ); document.write( "\"0.03%2A9%2B0.04%2A10=0.67\"\r
\n" ); document.write( "\n" ); document.write( "\"0.27%2B0.4=0.67\"\r
\n" ); document.write( "\n" ); document.write( "\"0.67=0.67\"\r
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