Dr. Watson received a $15 gift card to download music for her mp3 player. Each Song costs $1.50. Find the equation that represents the remaining balance on the gift card after x downloads. What is a suitable domain for this function?

y = -1.50x + 15, Domain is from 0 to 10

Step-by-step explanation:

First, look at the question carefully and highlight all the words that are important. We know that the 15 dollar giftcard is important, and we know that each song costs 1 dollar and 50 cents is important. We will make an equation out of this information. Since she is spending money, the value of X will be negated. She starts out with 15 dollars, so that will be our y-intercept. From this, the equation is y = -1.50x + 15. Next, let's look at the domain. We can see that the question asks for a suitable domain, not the domain of the function. Since she didn't have more than 15 dollars from her gift card, any domain from negative infinity until 0 will be crossed out. The x-intercept of this equation is 10, so any value above 10 will be crossed out since you cannot spend more money than you were given. The domain would now be from 1 to 10.

47 - 90 = 43

43 - 180 = x

x = 137