Question

The function f(x) = 0.11x + 43 relates how much Derek pays for phone service, f(x), to the number of minutes, x, used for international calls in a month. What is the value and meaning of f(320)?

Answer 1

f(x) = 0.11x + 43

f(320) = 0.11(320) + 43
f(320) = 35.20 + 43
f(320) = 78.20

so the value of f(320) is 78.20......and this is saying that for 320 minutes, his phone service would charge him $ 78.20