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.