document.write( "Question 120563: The sum of two numbers is 50 and their difference is 18. Find the numbers.\r
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Algebra.Com's Answer #88380 by jim_thompson5910(35256)\"\" \"About 
You can put this solution on YOUR website!
If the \"sum of two numbers is 50\", then we have the first equation \"x%2By=50\"\r
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\n" ); document.write( "\n" ); document.write( "If \"their difference is 18\", then we have the second equation \"x-y=18\"\r
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Solved by pluggable solver: Solving a linear system of equations by subsitution

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\n" ); document.write( " Lets start with the given system of linear equations
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\n" ); document.write( " \"1%2Ax%2B1%2Ay=50\"
\n" ); document.write( " \"1%2Ax-1%2Ay=18\"
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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( " \"1%2Ay=50-1%2Ax\"Subtract \"1%2Ax\" from both sides
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\n" ); document.write( " \"y=%2850-1%2Ax%29\" Divide both sides by 1.
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\n" ); document.write( " Which breaks down and reduces to
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\n" ); document.write( " \"y=50-1%2Ax\" Now we've fully isolated y
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\n" ); document.write( " Since y equals \"50-1%2Ax\" we can substitute the expression \"50-1%2Ax\" into y of the 2nd equation. This will eliminate y so we can solve for x.
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\n" ); document.write( " \"1%2Ax%2B-1%2Ahighlight%28%2850-1%2Ax%29%29=18\" Replace y with \"50-1%2Ax\". Since this eliminates y, we can now solve for x.
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\n" ); document.write( " \"1%2Ax-1%2A%2850%29-1%28-1%29x=18\" Distribute -1 to \"50-1%2Ax\"
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\n" ); document.write( " \"1%2Ax-50%2B1%2Ax=18\" Multiply
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\n" ); document.write( " \"1%2Ax-50%2B1%2Ax=18\" Reduce any fractions
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\n" ); document.write( " \"1%2Ax%2B1%2Ax=18%2B50\"Add \"50\" to both sides
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\n" ); document.write( " \"1%2Ax%2B1%2Ax=68\" Combine the terms on the right side
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\n" ); document.write( " \"2%2Ax=68\" Now combine the terms on the left side.
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\n" ); document.write( " \"cross%28%281%2F2%29%282%2F1%29%29x=%2868%2F1%29%281%2F2%29\" Multiply both sides by \"1%2F2\". This will cancel out \"2%2F1\" and isolate x
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\n" ); document.write( " So when we multiply \"68%2F1\" and \"1%2F2\" (and simplify) we get
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\n" ); document.write( " \"x=34\" <---------------------------------One answer
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\n" ); document.write( " Now that we know that \"x=34\", lets substitute that in for x to solve for y
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\n" ); document.write( " \"1%2834%29-1%2Ay=18\" Plug in \"x=34\" into the 2nd equation
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\n" ); document.write( " \"34-1%2Ay=18\" Multiply
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\n" ); document.write( " \"-1%2Ay=18-34\"Subtract \"34\" from both sides
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\n" ); document.write( " \"-1%2Ay=-16\" Combine the terms on the right side
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\n" ); document.write( " \"cross%28%281%2F-1%29%28-1%29%29%2Ay=%28-16%2F1%29%281%2F-1%29\" Multiply both sides by \"1%2F-1\". This will cancel out -1 on the left side.
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\n" ); document.write( " \"y=-16%2F-1\" Multiply the terms on the right side
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\n" ); document.write( " \"y=16\" Reduce
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\n" ); document.write( " So this is the other answer
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\n" ); document.write( " \"y=16\"<---------------------------------Other answer
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\n" ); document.write( " So our solution is
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\n" ); document.write( " \"x=34\" and \"y=16\"
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\n" ); document.write( " which can also look like
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\n" ); document.write( " (\"34\",\"16\")
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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( " \"1%2Ax%2B1%2Ay=50\"
\n" ); document.write( " \"1%2Ax-1%2Ay=18\"
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\n" ); document.write( " we get
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\n" ); document.write( " graph of \"1%2Ax%2B1%2Ay=50\" (red) and \"1%2Ax-1%2Ay=18\" (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 (\"34\",\"16\"). This verifies our answer.
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\n" ); document.write( " Plug in (\"34\",\"16\") into the system of equations
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\n" ); document.write( " Let \"x=34\" and \"y=16\". Now plug those values into the equation \"1%2Ax%2B1%2Ay=50\"
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\n" ); document.write( " \"1%2A%2834%29%2B1%2A%2816%29=50\" Plug in \"x=34\" and \"y=16\"
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\n" ); document.write( " \"34%2B16=50\" Multiply
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\n" ); document.write( " \"50=50\" Add
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\n" ); document.write( " \"50=50\" Reduce. Since this equation is true the solution works.
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\n" ); document.write( " So the solution (\"34\",\"16\") satisfies \"1%2Ax%2B1%2Ay=50\"
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\n" ); document.write( " Let \"x=34\" and \"y=16\". Now plug those values into the equation \"1%2Ax-1%2Ay=18\"
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\n" ); document.write( " \"1%2A%2834%29-1%2A%2816%29=18\" Plug in \"x=34\" and \"y=16\"
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\n" ); document.write( " \"34-16=18\" Multiply
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\n" ); document.write( " \"18=18\" Add
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\n" ); document.write( " \"18=18\" Reduce. Since this equation is true the solution works.
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\n" ); document.write( " So the solution (\"34\",\"16\") satisfies \"1%2Ax-1%2Ay=18\"
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\n" ); document.write( " Since the solution (\"34\",\"16\") satisfies the system of equations
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\n" ); document.write( " \"1%2Ax%2B1%2Ay=50\"
\n" ); document.write( " \"1%2Ax-1%2Ay=18\"
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\n" ); document.write( " this verifies our answer.
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\n" ); document.write( "\n" ); document.write( "So the two numbers are 34 and 16
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