Question

Refer to the table of long distance rates. Write an expression that can be used to find the cost of an n-minute long distance call, where n is at least 5 minutes.

Answer 1

a(n) = 0.55 + (n -5)0.07

Explanation:

The cost goes up $0.07 for each additional minute, so that is the slope of the linear function. In point-slope form the equation can be written ...

... a(n) - 0.55 = 0.07(n -5)

adding 0.55, and rearranging slightly, this becomes ...

... a(n) = 0.55 +(n -5)0.07