Question

State your variables and what they represent. Write a linear function describing the situation. Use the function to solve the problem.

A phone costs $8 per month, plus 10 cents per message unit. How much is the monthly bill if 40 message units are used?

Answer 1

y = 0.10x + 8, $12

Explanation:

y = monthly bill

x = number of message units

Each message unit costs $0.10, so the cost of x message units is 0.10x. The phone adds $8 to the monthly bill. Therefore:

y = 0.10x + 8

If x = 40, then:

y = 0.10 (40) + 8

y = 4 + 8

y = 12

The monthly bill is $12.