The average number of pages Irene read in a certain number of days was 18. In the next eight days, Irene read another 12 pages. As a result, the average number of pages she read decreased to 15. How many days did Irene read in total?
| |
At first |
In the end |
| Number |
1 u |
1 u + 8 |
| Value |
18 |
15 |
| Number x value |
18 u |
15 u + 120 |
Number of days that Irene read at first = 1 u
Number of pages that Irene read at first
= 1 u x 18
= 18 u
Number of pages that Irene read in the end = 18 u + 12
Number of days that Irene read in the end = 1 u + 8
Number of pages that Irene read in the end
= 15 x (1 u + 8)
= 15 u + 120
18 u + 12 = 15 u + 120
18 u - 15 u = 120 - 12
3 u = 108
1 u = 108 ÷ 3 = 36
Number of days that Irene read in the end
= 1 u + 8
= 36 + 8
= 44
Answer(s): 44
