financial algebra HW help!!

Question

the lisbon's new heat pump cost $4000. They bought it to replace their old furnace and air conditioner which cost about $2800 a year to run. The heat pump will save them approximately 39% a year. In how many years will the heat pump pay for itself? Round to the nearest tenth.

Answer 1

They will save .39 * 2800 per year = 1092.

4000/1092 = 3.663004, rounded to nearest tenth is 3.7 years