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)?
a. $78.20; this is the amount derek pays for 320 months of service
b. $78.20; this is the amount derek pays for 320 minutes of international calls
c. $92.50; this is the amount derek pays for 320 months of service
d. $92.50; this is the amount derek pays for 320 minutes of international calls