Question

Alicia Keys's new album As I Am is climbing the charts, and the manager of Tip Top Tunes expects to sell a lot of copies. Because she has limited shelf space, she can't put out all her copies of the CD at once. On Monday morning, she stocked the display with 40 copies. By the end of the day, some of the copies had been sold. On Tuesday morning, she counted the number of copies left and then added that many more to the shelf. In other words, she doubled the number that was left in the display. At the end of the day, she discovered that she had sold the exact same number of copies as had been sold on Monday. On Wednesday morning, the manager decided to triple the number of copies that had been left in the case after Tuesday. Amazingly, she sold the same number of copies on Wednesday as she had on each of the first two days! But this time, at the end of the day the display case was empty. How many copies of the As I Am CD did she sell each day?

Answer 1

About 4.44

Explanation:

Let x represent the unknown amount of CD's sold each day. Thus, the linear equation is formed:

40-x = 2x + 3 (2x) Next collect like terms by adding x to both sides.

40-x+x= x + 2x + 3 (2x)

40 = 3x + 3 (2x)

40 = 3x + 6x

40= 9x

40/9 = 9x/9

x= 4.44

Note: 2x represents doubling up the sales amount, which was left.

3x represents tripling the sales amount left.