SOLUTION: 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 use

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./
Answer by mananth(16946) (Show Source): You can put this solution on YOUR website!
x cost of unit of electricity
y cost of unit of gas

300.00 x + 140.00 y = 106.20

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

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