The average number of pages Dana read in a certain number of days was 16. In the next four days, Dana read another 91 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 + 4 |
| Value |
16 |
19 |
| Number x value |
16 u |
19 u + 76 |
Number of days that Dana read at first = 1 u
Number of pages that Dana read at first
= 1 u x 16
= 16 u
Number of pages that Dana read in the end = 16 u + 91
Number of days that Dana read in the end = 1 u + 4
Number of pages that Dana read in the end
= 19 x (1 u + 4)
= 19 u + 76
19 u + 76 = 16 u + 91
19 u - 16 u = 91 - 76
3 u = 15
1 u = 15 ÷ 3 = 5
Number of days that Dana read in the end
= 1 u + 4
= 5 + 4
= 9
Answer(s): 9
