Question

Suppose a video store charges non-members $4 to rent a video. A membership costs $21 and then videos cost only $2.50 to rent. How many videos would you need to rent in order to justify a membership?

Answer 1

You need to rent `14` videos, and you'll pay the same amount for both. Renting `15` will make the membership a better method of payment.

Explanation:

We can create an equation. Say the number of videos you rent is given by `n`. We can write that, if we rent `n` videos without membership, we'll have to pay `4n`. If we rent the same amount of videos with membership, we'll have to pay `21+2.5n`.

To find the value of `n` such that the amount you pay without membership is equal to the amount you pay with, we write:

`4n=21+2.5n`

`1.5n=21`

`n=21/1.5`

`n=14`

You need to rent `14` videos, and you'll pay the same amount for both. Renting `15` will make the membership a better method of payment.