Question

Renata wins a $20 gift card to an online music site. After Renata purchases 16 songs, the gift card has a remaining balance of $0. Which equation represents the relationship between y, the remaining balance on Renata’s gift card, and x, the number of songs purchased?
4x + 5y = –100
5x + 4y = 80
4x + 5y = 16
5x + 4y = 20

Answer 1

Firstly we need to find the gradient of the line, which in this case is the cost of one song. If the gift card has $20 and after 16 songs it has $0 that means that the price of one song would be 20/16 = 5/4 (= $1.25).

We know that the y-intercept is (0, 20), since when 0 songs are purchased the gift card has $20. Thus using the equation form y = mx + c we get:
y = 5/4 + 20

Now if we multiply both sides by 4 we get:
4y + 5x = 80
This is the same as the second answer (5x + 4y = 80), thus B is correct :)

Answer 2

Answer: B. 5x + 4y = 80

Step-by-step explanation: Brainly User

Firstly we need to find the gradient of the line, which in this case is the cost of one song. If the gift card has $20 and after 16 songs it has $0 that means that the price of one song would be 20/16 = 5/4 (= $1.25).

We know that the y-intercept is (0, 20), since when 0 songs are purchased the gift card has $20. Thus using the equation form y = mx + c we get:

y = 5/4 + 20

Now if we multiply both sides by 4 we get:

4y + 5x = 80

This is the same as the second answer (5x + 4y = 80),