Question

During one month, a homeowner used 600 units of electricity and 100 units of gas for a total cost of 390. The next month, 400 units of electricity and 250 units of gas were used for a total cost of $326. Find the cost per unit of gas.

Answer 1

Answer:

$0.36

Step-by-step explanation:

Let the cost per unit of electricity  = e

Let the cost per unit of gas  = g

  a homeowner used 600 units of electricity and 100 units of gas for a total cost of 390;

   600e + 100g  = 390  ----- i

  400 units of electricity and 250 units of gas were used for a total cost of $326.

     400e + 250g  = 326 ----- ii

Now we have two equations, and we solve for g;

     600e + 100g  = 390  ----- i

     400e + 250g  = 326 ----- ii  

Multiply equation i by 4 and equation ii by 6;

    2400e + 400g  = 1560 ---- iii

    2400e + 1500g  = 1956 ---- iv

Subtract equation iii from iv;

                  1100g  = 396

                       g  = $\frac{396}{1100}$   = 0.36

Cost per unit of gas $0.36