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

B

Explanation:

i think its b cuz yea

Answer 2

5x + 4y = 80

Explanation:
First, let us look at the given:

x = The number of songs purchased

y = The remaining balance of Renata's gift card

Coordinates:

1. (16,0)

2. (0,20)

Now let's look at the unknown:

Slope =?

Since we have the coordinates we can easily apply the slope formula

Now that we have our slope we can use either point-slope formation or slope-intercept formation, just pick whichever one you're comfortable with.

Point-slope formation

y - y1 = slope (x - x1)

Now just plug in the numbers:

y - 0 = 20/-16 (x - 16)

Now you multiply both sides by -16 to get rid of the fraction

-16(y - 0) = -16 (20/-16) (x - 16)

-16y - 0 = 20 (x - 16)

-16y = 20x - 320

Now subtract 20 from both sides.

-16y - 20x = 20x - 20x - 320

-20x - 16y = -320

Now we need to simplify both sides so we divide both sides by 4

-5x - 4y = -80

Now, remember, one of the rules of standard formation is that the coefficient of x cannot be smaller than zero. So you need to multiply both sides by -1.

-1 (-5x - 4y) = (-80) -1

5x + 4y = 80