Question

A city's water company charges a fee of $30 a month in addition to $0.3 per every gallon used. Using the function c = 0.35x + 30, where c is the total cost per month for water services and x is gallons used. Which of the following points on the graph accurately represents a monthly usage of 1,400 gallons?

(520, 1400)
(490, 1,400)
(1,400, 520)
(1,400, 490)

Answer 1

Use x = 1400 in c = 0.35x + 30:

c = 0.35(1400) + 30 = 490 + 30 = 520.

So the point is (1400, 520).