Answer:

The value of f(320) = $78.2.

And the meaning of f(320) is the the amount $ 78.2 Derek pays for 320 minutes of international calls.

Step-by-step explanation:

Given the function: f(x) = 0.11x + 43              ……[1]

where;

x represents the number of minutes used for international calls in a month and

f(x) represents the cost.

Find the value of f(320);

Substitute the value of x =320 in [1] we have;

f(320) = 0.11(320) +43

or

f(320) = 35.2+43 = 78.2

Therefore, the value of f(320) is, $78.2.

The meaning of f(320) means that $78.2 is the amount Derek pays for 320 minutes of international calls.