Question 277666
By installing a $120 thermostat that reduces the temperature setting at night, a family hopes to cut its annual bill for heating oil by 8 percent, and thereby recover the cost of the thermostat in fuel savings after 2 years. What was the family's annual fuel bill before installing the thermostat?


Let the annual bill for oil be x

reduction is 8/100 *x

for 2 years the reduction will be 8x/100 * 2 

8x/100 * 2 = 120

16x/100 =120

16x=12000

x=12000/16

= 750

annual oil bill was $750