Answer:
D) f(x) = 20x + 5
Explanation:
A gym membership has an application fee of $5 plus $20 per month.
You pay a initial fee($5) and then a constant fee of $20 a month. That is, after x months you will have paid f(x) = 5 + 20x.
The correct answer is:
D) f(x) = 20x + 5