Answer:
8 years
Step-by-step explanation:
There are 50 lights present in the building and each light cost $50. Therefore the cost of changing all the bulbs is:
Cost = number of lights * cost per light = 50 lights * $50 = $2500
Changing the lights in the building save the company $305 per year in energy cost. Therefore, the number of years required for the new lights to pay for themselves is:
number of years = cost of changing bulbs / money saved per year
number of years = $2500 / $305 per year = 8.2
number of years = 8 years to the nearest year