document.write( "Question 92529: Adult tickets for a play cost $20 and child tickets cost $16. If there were 27 people at a performance and the theater collected $464 from ticket sales, how many adults and how many children attended the play?\r
\n" ); document.write( "\n" ); document.write( "A) 10 adults and 21 children
\n" ); document.write( "B) 9 adults and 20 children
\n" ); document.write( "C) 8 adults and 19 children
\n" ); document.write( "D) 7 adults and 18 children
\n" ); document.write( "Thank you for any help...
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Algebra.Com's Answer #67361 by jim_thompson5910(35256)\"\" \"About 
You can put this solution on YOUR website!
Let x=# of adults, y=# of children\r
\n" ); document.write( "\n" ); document.write( "Translate the word problem into a system of equations:\r
\n" ); document.write( "\n" ); document.write( "\"20x%2B16y=464\" the cost of the adults' tickets plus the cost of the children's tickets is equal to $464\r
\n" ); document.write( "\n" ); document.write( "\"x%2By=27\" the sum of all who attended is 27\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( " \"20%2Ax%2B16%2Ay=464\"
\n" ); document.write( " \"1%2Ax%2B1%2Ay=27\"
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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( " \"16%2Ay=464-20%2Ax\"Subtract \"20%2Ax\" from both sides
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\n" ); document.write( " \"y=%28464-20%2Ax%29%2F16\" Divide both sides by 16.
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\n" ); document.write( " Which breaks down and reduces to
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\n" ); document.write( " \"y=29-%285%2F4%29%2Ax\" Now we've fully isolated y
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\n" ); document.write( " Since y equals \"29-%285%2F4%29%2Ax\" we can substitute the expression \"29-%285%2F4%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( " \"1%2Ax%2B1%2Ahighlight%28%2829-%285%2F4%29%2Ax%29%29=27\" Replace y with \"29-%285%2F4%29%2Ax\". Since this eliminates y, we can now solve for x.
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\n" ); document.write( " \"1%2Ax%2B1%2A%2829%29%2B1%28-5%2F4%29x=27\" Distribute 1 to \"29-%285%2F4%29%2Ax\"
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\n" ); document.write( " \"1%2Ax%2B29-%285%2F4%29%2Ax=27\" Multiply
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\n" ); document.write( " \"1%2Ax%2B29-%285%2F4%29%2Ax=27\" Reduce any fractions
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\n" ); document.write( " \"1%2Ax-%285%2F4%29%2Ax=27-29\" Subtract \"29\" from both sides
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\n" ); document.write( " \"1%2Ax-%285%2F4%29%2Ax=-2\" Combine the terms on the right side
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\n" ); document.write( " \"%284%2F4%29%2Ax-%285%2F4%29x=-2\" Make 1 into a fraction with a denominator of 4
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\n" ); document.write( " \"%28-1%2F4%29%2Ax=-2\" Now combine the terms on the left side.
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\n" ); document.write( " \"cross%28%284%2F-1%29%28-1%2F4%29%29x=%28-2%2F1%29%284%2F-1%29\" Multiply both sides by \"4%2F-1\". This will cancel out \"-1%2F4\" and isolate x
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\n" ); document.write( " So when we multiply \"-2%2F1\" and \"4%2F-1\" (and simplify) we get
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\n" ); document.write( " \"x=8\" <---------------------------------One answer
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\n" ); document.write( " Now that we know that \"x=8\", lets substitute that in for x to solve for y
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\n" ); document.write( " \"1%288%29%2B1%2Ay=27\" Plug in \"x=8\" into the 2nd equation
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\n" ); document.write( " \"8%2B1%2Ay=27\" Multiply
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\n" ); document.write( " \"1%2Ay=27-8\"Subtract \"8\" from both sides
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\n" ); document.write( " \"1%2Ay=19\" Combine the terms on the right side
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\n" ); document.write( " \"cross%28%281%2F1%29%281%29%29%2Ay=%2819%2F1%29%281%2F1%29\" Multiply both sides by \"1%2F1\". This will cancel out 1 on the left side.
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\n" ); document.write( " \"y=19%2F1\" Multiply the terms on the right side
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\n" ); document.write( " \"y=19\" Reduce
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\n" ); document.write( " So this is the other answer
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\n" ); document.write( " \"y=19\"<---------------------------------Other answer
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\n" ); document.write( " So our solution is
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\n" ); document.write( " \"x=8\" and \"y=19\"
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\n" ); document.write( " which can also look like
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\n" ); document.write( " (\"8\",\"19\")
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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( " \"20%2Ax%2B16%2Ay=464\"
\n" ); document.write( " \"1%2Ax%2B1%2Ay=27\"
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\n" ); document.write( " we get
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\n" ); document.write( "
\n" ); document.write( " graph of \"20%2Ax%2B16%2Ay=464\" (red) and \"1%2Ax%2B1%2Ay=27\" (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 (\"8\",\"19\"). This verifies our answer.
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\n" ); document.write( " -----------------------------------------------------------------------------------------------
\n" ); document.write( " Check:
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\n" ); document.write( " Plug in (\"8\",\"19\") into the system of equations
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\n" ); document.write( " Let \"x=8\" and \"y=19\". Now plug those values into the equation \"20%2Ax%2B16%2Ay=464\"
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\n" ); document.write( " \"20%2A%288%29%2B16%2A%2819%29=464\" Plug in \"x=8\" and \"y=19\"
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\n" ); document.write( "
\n" ); document.write( " \"160%2B304=464\" Multiply
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\n" ); document.write( " \"464=464\" Add
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\n" ); document.write( " \"464=464\" Reduce. Since this equation is true the solution works.
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\n" ); document.write( "
\n" ); document.write( " So the solution (\"8\",\"19\") satisfies \"20%2Ax%2B16%2Ay=464\"
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\n" ); document.write( "
\n" ); document.write( " Let \"x=8\" and \"y=19\". Now plug those values into the equation \"1%2Ax%2B1%2Ay=27\"
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\n" ); document.write( " \"1%2A%288%29%2B1%2A%2819%29=27\" Plug in \"x=8\" and \"y=19\"
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\n" ); document.write( "
\n" ); document.write( " \"8%2B19=27\" Multiply
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\n" ); document.write( " \"27=27\" Add
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\n" ); document.write( "
\n" ); document.write( " \"27=27\" Reduce. Since this equation is true the solution works.
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\n" ); document.write( "
\n" ); document.write( " So the solution (\"8\",\"19\") satisfies \"1%2Ax%2B1%2Ay=27\"
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\n" ); document.write( "
\n" ); document.write( " Since the solution (\"8\",\"19\") satisfies the system of equations
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\n" ); document.write( "
\n" ); document.write( " \"20%2Ax%2B16%2Ay=464\"
\n" ); document.write( " \"1%2Ax%2B1%2Ay=27\"
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\n" ); document.write( " this verifies our answer.
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\n" ); document.write( "\n" ); document.write( "So 8 adults and 19 children attended. This means the answer is C)
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