document.write( "Question 1179788: During one month, a homeowner used 300 units of electricity and 140 units of gas for a total cost of $106.20. The next month, 250 units of electricity and 250 units of gas were used for a total cost of $112.50. Find the cost per unit of gas./ \n" ); document.write( "

Algebra.Com's Answer #809378 by mananth(16946) $\"\"$ $\"About$

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x cost of unit of electricity
\n" ); document.write( " y cost of unit of gas
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\n" ); document.write( "300.00 x + 140.00 y = 106.20
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\n" ); document.write( "250.00 x + 250.00 y = 112.50 .............2
\n" ); document.write( "Eliminate y
\n" ); document.write( "multiply (1)by -250.00
\n" ); document.write( "Multiply (2) by 140.00
\n" ); document.write( "-75000.00 x -35000.00 y = -26550.00
\n" ); document.write( "35000.00 x 35000.00 y = 15750.00
\n" ); document.write( "Add the two equations
\n" ); document.write( "-40000.00 x = -10800.00
\n" ); document.write( "/ -40000.00
\n" ); document.write( "x = 0.27
\n" ); document.write( "plug value of x in (1)
\n" ); document.write( "300.00 x + 140.00 y = 106.20
\n" ); document.write( "81.00 + 140.00 y = 106.20
\n" ); document.write( " 140.00 y = 25.20
\n" ); document.write( " y = 0.18
\n" ); document.write( "Ans x = 0.27
\n" ); document.write( " y = 0.18
\n" ); document.write( " 27 cents cost of unit of electricity
\n" ); document.write( " 18 cents cost of unit of gas
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