document.write( "Question 153240: you have used all of a $50 gift certificate watching movies at the local theater. Afternoon movies are $4 and evening movies are $6. you have watched a total of 10 movies. HOw much have you spent on evening movies? \n" ); document.write( "
Algebra.Com's Answer #112770 by jim_thompson5910(35256)\"\" \"About 
You can put this solution on YOUR website!
Let x=# of $6 movies and y=# of $4 movies\r
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\n" ); document.write( "\n" ); document.write( "Since \"you have watched a total of 10 movies\", this means that the first equation is \"x%2By=10\"\r
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\n" ); document.write( "\n" ); document.write( "Also, since you only have $50 to spend, this means that the second equation is \"6x%2B4y=50\"\r
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\n" ); document.write( "\n" ); document.write( "So we have the system of equations:\r
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\n" ); document.write( "\n" ); document.write( "\"system%28x%2By=10%2C6x%2B4y=50%29\"\r
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\n" ); document.write( "\n" ); document.write( "Let's use substitution to solve this system.\r
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\n" ); document.write( "\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 solve for y.\r
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\n" ); document.write( "\n" ); document.write( "So let's isolate y in the first equation\r
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\n" ); document.write( "\n" ); document.write( "\"x%2By=10\" Start with the first equation\r
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\n" ); document.write( "\n" ); document.write( "\"y=10-x\" Subtract \"x\" from both sides\r
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\n" ); document.write( "\n" ); document.write( "\"y=-x%2B10\" Rearrange the equation\r
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\n" ); document.write( "\n" ); document.write( "Since \"y=-x%2B10\", we can now replace each \"y\" in the second equation with \"-x%2B10\" to solve for \"x\"\r
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\n" ); document.write( "\n" ); document.write( "\"6x%2B4highlight%28%28-x%2B10%29%29=50\" Plug in \"y=-x%2B10\" into the first equation. In other words, replace each \"y\" with \"-x%2B10\". Notice we've eliminated the \"y\" variables. So we now have a simple equation with one unknown.\r
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\n" ); document.write( "\n" ); document.write( "\"6x%2B%284%29%28-1%29x%2B%284%29%2810%29=50\" Distribute \"4\" to \"-x%2B10\"\r
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\n" ); document.write( "\n" ); document.write( "\"6x-4x%2B40=50\" Multiply\r
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\n" ); document.write( "\n" ); document.write( "\"2x%2B40=50\" Combine like terms on the left side\r
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\n" ); document.write( "\n" ); document.write( "\"2x=50-40\"Subtract 40 from both sides\r
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\n" ); document.write( "\n" ); document.write( "\"2x=10\" Combine like terms on the right side\r
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\n" ); document.write( "\n" ); document.write( "\"x=%2810%29%2F%282%29\" Divide both sides by 2 to isolate x\r
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\n" ); document.write( "\n" ); document.write( "\"x=5\" Divide\r
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\n" ); document.write( "\n" ); document.write( "-----------------First Answer------------------------------\r
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\n" ); document.write( "\n" ); document.write( "So the first part of our answer is: \"x=5\"\r
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\n" ); document.write( "\n" ); document.write( "Since we know that \"x=5\" we can plug it into the equation \"y=-x%2B10\" (remember we previously solved for \"y\" in the first equation).\r
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\n" ); document.write( "\n" ); document.write( "\"y=-x%2B10\" Start with the equation where \"y\" was previously isolated.\r
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\n" ); document.write( "\n" ); document.write( "\"y=-%285%29%2B10\" Plug in \"x=5\"\r
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\n" ); document.write( "\n" ); document.write( "\"y=-5%2B10\" Multiply\r
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\n" ); document.write( "\n" ); document.write( "\"y=5\" Combine like terms \r
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\n" ); document.write( "\n" ); document.write( "-----------------Second Answer------------------------------\r
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\n" ); document.write( "\n" ); document.write( "So the second part of our answer is: \"y=5\"\r
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\n" ); document.write( "\n" ); document.write( "-----------------Summary------------------------------\r
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\n" ); document.write( "\n" ); document.write( "So our answers are:\r
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\n" ); document.write( "\n" ); document.write( "\"x=5\" and \"y=5\"\r
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\n" ); document.write( "\n" ); document.write( "This means that you bought 5 $6 movies and 5 $4 movies\r
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