Question

During one month a homeowner uses 200 units of electricity and 130 units of gas for a total cost of $82.80. The next month, 220 units of electricity and 200 units of gas were used for a total cost of $100.20. Find the cost per unit of gas

Answer 1

let the per unit cost of electricity be x and gas be y

200x + 130y = 82.80

220x + 200y = 100.20

solve by subtraction method