I could use some help （；へ：）

Question

Latoya wants to save $900 to buy a TV. She saves $18 each week. The amount, A (in dollars), that she still needs after w weeks is given by the following function.

=Aw−90018w

Answer the following questions:

a) How much money does Layota need after 5 weeks?

b) If Layota still needs $594, how many weeks has she been saving?

Thanks, I'd really appreciate if I could get help with this.

Answer 1

The function should be A = 900 - 18w

a) To find out how much she needs after 5 weeks, plug in 5 for w

A = 900 - 18(5) = 900 - 90 = 810

She needs $810 after 5 weeks.

b) To find out how many weeks she's been saving, given she has $594, plug in 594 for A

594 = 900 - 18w

18w = 900 - 594

18w = 306

w = 17

She has been saving 17 weeks.