How much credit is left on the prepaid phone card?

Question:

If 75 units of credit have been used on a prepaid phone card with an initial credit of $20.75 and a decrement of $0.09 per unit of use, how much credit is left on the card?

Answer:

The remaining credit on the prepaid phone card can be calculated using the equation C(x)=20.75-0.09x.

To calculate the remaining credit on the prepaid phone card after using 75 units of credit, we substitute x=75 into the equation:

C(75) = 20.75 - 0.09(75)

C(75) = 20.75 - 6.75

C(75) = 14

Therefore, there is $14 credit left on the prepaid phone card after using 75 units.