The average number of pages Rachel read in a certain number of days was 15. In the next four days, Rachel read another 36 pages. As a result, the average number of pages she read decreased to 12. How many days did Rachel read in total?
| |
At first |
In the end |
| Number |
1 u |
1 u + 4 |
| Value |
15 |
12 |
| Number x value |
15 u |
12 u + 48 |
Number of days that Rachel read at first = 1 u
Number of pages that Rachel read at first
= 1 u x 15
= 15 u
Number of pages that Rachel read in the end = 15 u + 36
Number of days that Rachel read in the end = 1 u + 4
Number of pages that Rachel read in the end
= 12 x (1 u + 4)
= 12 u + 48
15 u + 36 = 12 u + 48
15 u - 12 u = 48 - 36
3 u = 12
1 u = 12 ÷ 3 = 4
Number of days that Rachel read in the end
= 1 u + 4
= 4 + 4
= 8
Answer(s): 8
