Question

Rachel works at a bookstore. On Tuesday, she sold twice as many books as she did on Monday. On Wednesday, she sold 6 fewer books than she did on Tuesday. During the three days Rachel sold 19 books. Create an equation that can be used to find m, the number of books Rachel sold on Monday.

Answer 1

The answer is 5 books.

m - the number of books sold on Monday
t - the number of books sold on Tuesday
w - the number of books sold on Wednesday

On Tuesday, she sold twice as many books as she did on Monday: t = 2m
On Wednesday, she sold 6 fewer books than she did on Tuesday: w = t - 6
During the three days Rachel sold 19 books: m + t + w = 19

t = 2m
w = t - 6 = 2m - 6
m + t + w = 19
______
Substitute t and w in the third equation:
m + 2m + 2m - 6 = 19
5m - 6 = 19
5m = 19 + 6
5m = 25
m = 25 : 5
m = 5