The average number of pages Dana read in a certain number of days was 15. In the next three days, Dana read another 89 pages. As a result, the average number of pages she read increased to 19. How many days did Dana read in total?
| |
At first |
In the end |
| Number |
1 u |
1 u + 3 |
| Value |
15 |
19 |
| Number x value |
15 u |
19 u + 57 |
Number of days that Dana read at first = 1 u
Number of pages that Dana read at first
= 1 u x 15
= 15 u
Number of pages that Dana read in the end = 15 u + 89
Number of days that Dana read in the end = 1 u + 3
Number of pages that Dana read in the end
= 19 x (1 u + 3)
= 19 u + 57
19 u + 57 = 15 u + 89
19 u - 15 u = 89 - 57
4 u = 32
1 u = 32 ÷ 4 = 8
Number of days that Dana read in the end
= 1 u + 3
= 8 + 3
= 11
Answer(s): 11
