document.write( "Question 950665: I am not very good with word problems, and my parents can't help me right now because they are busy, but i think i have a start and i was hoping to confirm my structure of solving this question. \r
\n" ); document.write( "\n" ); document.write( "At Happy Burger you can get one order of fries and one burger for $7.20. You can also get three orders of fries and seven burgers for $38.60. What is the cost of each item?\r
\n" ); document.write( "\n" ); document.write( "1x + 1y = 7.20
\n" ); document.write( "[-1x -1x]
\n" ); document.write( "y = -1x + 7.20\r
\n" ); document.write( "\n" ); document.write( "3x + 7y = 38.60
\n" ); document.write( "[-3x -3x]
\n" ); document.write( "7y = -3x + 38.60
\n" ); document.write( "[/7 /7 /7]
\n" ); document.write( "y = -3/7x + 5.51 \r
\n" ); document.write( "\n" ); document.write( " \n" ); document.write( "

Algebra.Com's Answer #580562 by MathTherapy(10553) $\"\"$ $\"About$

You can put this solution on YOUR website!
I am not very good with word problems, and my parents can't help me right now because they are busy, but i think i have a start and i was hoping to confirm my structure of solving this question. \r
\n" ); document.write( "\n" ); document.write( "At Happy Burger you can get one order of fries and one burger for $7.20. You can also get three orders of fries and seven burgers for $38.60. What is the cost of each item?\r
\n" ); document.write( "\n" ); document.write( "1x + 1y = 7.20
\n" ); document.write( "[-1x -1x]
\n" ); document.write( "y = -1x + 7.20\r
\n" ); document.write( "\n" ); document.write( "3x + 7y = 38.60
\n" ); document.write( "[-3x -3x]
\n" ); document.write( "7y = -3x + 38.60
\n" ); document.write( "[/7 /7 /7]
\n" ); document.write( "y = -3/7x + 5.51
\n" ); document.write( "

Why are you solving each system for y? You don't need to do that, unless you're planning to graph the system.\r
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document.write( "\n" );
document.write( "With x being the cost of an order of fries, and y being the cost of a burger, the following system is derived:
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document.write( "   x +  y =    7.2 ----- eq (i)	
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document.write( "  3x + 7y =   38.6 ----- eq (ii)	
\n" );
document.write( "- 3x - 3y = - 21.6 ----- Multiplying eq (i) by - 3 ------ eq (iii)
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document.write( "       4y =   17 ------- Adding eqs (iii) & (ii)	
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document.write( "y, or cost of a burger = , or 	\r
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document.write( "\n" );
document.write( "x + 4.25 = 7.2 --------- Substituting $4.25 for y in eq (i)
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document.write( "x = 7.2 - 4.25
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document.write( "x, or cost of an order of fries =  \n" );
document.write( "

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