Question

There is a ​$40 fee to rent a chain​ saw, plus ​$9 per day. Let x represent the number of days the saw is rented and y represent the charge to the user in dollars. If the total charge is ​$184​, for how many days is the saw​ rented?

Answer 1

16 days

Explanation:

y = 9x + 40

Do you see how that equation fits the words? The '40' term is the $40 base fee, and then you're charged $9 for every day you use it, so that's the '9x' term.

y is the total cost, which they give us, and they want us to solve for x, the number of days. So:

y = 9x + 40 Subtract 40 from both sides:

y - 40 = 9x Now divide both sides by 9:

(y-40)/9 = x Turn it around and plug in the value of y:

x = (184 - 40)/9 = 144/9 = 16 days

Check our work by multiplying $9 per day times 16 days to get $144, then adding the $40 base fee to get $184. Which is the cost they gave us, so it checks out.