document.write( "Question 949078: During one month, a homeowner used 200 units of electricity and 130 units of gas for a total cost of $71.50. The next month, 220 units of electricity and 200 units of gas were used for a total cost of $87.20. Find the cost per unit of gas.
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Algebra.Com's Answer #579351 by macston(5194)\"\" \"About 
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e=cost per unit of electricity; g=cost per unit of gas
\n" ); document.write( "200e+130g=$71.50 Multiply each side by 20/13
\n" ); document.write( "(4000/13)e+200g=$110.00
\n" ); document.write( "220e+200g=$87.20 Subtract from above.
\n" ); document.write( "(4000/13)e-220e=$22.80
\n" ); document.write( "(4000/13)e-(2860/13)e=$22.80
\n" ); document.write( "(1140/13)e=$22.80
\n" ); document.write( "87.69e=$22.80
\n" ); document.write( "e=$0.26
\n" ); document.write( "200e+130g=$71.50
\n" ); document.write( "200($.26)+130g=$71.50
\n" ); document.write( "$52+130g=$71.50 Subtract $52 from each side
\n" ); document.write( "130g=$19.50 Divide each side by 130
\n" ); document.write( "g=$0.15 ANSWER: The cost of gas is $0.15 per unit.
\n" ); document.write( "CHECK:
\n" ); document.write( "220e+200g=$87.20
\n" ); document.write( "220($0.26)+200($0.15)=$87.20
\n" ); document.write( "$57.20+$30.00=$87.20
\n" ); document.write( "$87.20=$87.20
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