Answer:
cos to = $ 24
Step-by-step explanation:
When replacing the bulb only 25% of the energy is used, therefore
W = 0.25 100
W = 25 W
Let's look for the energy in the life of the bulb
E = 25 10⁻³ 12000
E = 300 Kwh
now we can calculate the cost using a direct proportion rule.
Cost = 0.08 300
cos to = $ 24