The average number of pages Yoko read in a certain number of days was 17. In the next three days, Yoko read another 81 pages. As a result, the average number of pages she read increased to 22. How many days did Yoko read in total?
| |
At first |
In the end |
| Number |
1 u |
1 u + 3 |
| Value |
17 |
22 |
| Number x value |
17 u |
22 u + 66 |
Number of days that Yoko read at first = 1 u
Number of pages that Yoko read at first
= 1 u x 17
= 17 u
Number of pages that Yoko read in the end = 17 u + 81
Number of days that Yoko read in the end = 1 u + 3
Number of pages that Yoko read in the end
= 22 x (1 u + 3)
= 22 u + 66
22 u + 66 = 17 u + 81
22 u - 17 u = 81 - 66
5 u = 15
1 u = 15 ÷ 5 = 3
Number of days that Yoko read in the end
= 1 u + 3
= 3 + 3
= 6
Answer(s): 6
