The average number of pages Victoria read in a certain number of days was 12. In the next four days, Victoria read another 81 pages. As a result, the average number of pages she read increased to 15. How many days did Victoria read in total?
| |
At first |
In the end |
| Number |
1 u |
1 u + 4 |
| Value |
12 |
15 |
| Number x value |
12 u |
15 u + 60 |
Number of days that Victoria read at first = 1 u
Number of pages that Victoria read at first
= 1 u x 12
= 12 u
Number of pages that Victoria read in the end = 12 u + 81
Number of days that Victoria read in the end = 1 u + 4
Number of pages that Victoria read in the end
= 15 x (1 u + 4)
= 15 u + 60
15 u + 60 = 12 u + 81
15 u - 12 u = 81 - 60
3 u = 21
1 u = 21 ÷ 3 = 7
Number of days that Victoria read in the end
= 1 u + 4
= 7 + 4
= 11
Answer(s): 11
