Answer:
Cost = 165.6 cents = $1.656
Step-by-step explanation:
First, we will calculate the total energy consumed by the bulb in a month:

where,
E = Energy Consumed = ?
P = power = 23 W
t = time = (1 month)(30 days/1 month)(24 h/1 day) = 720 h
Therefore,

Now, the cost will be:

Cost = 165.6 cents = $1.656