The average number of pages Xuan read in a certain number of days was 18. In the next seven days, Xuan read another 41 pages. As a result, the average number of pages she read decreased to 13. How many days did Xuan read in total?
| |
At first |
In the end |
| Number |
1 u |
1 u + 7 |
| Value |
18 |
13 |
| Number x value |
18 u |
13 u + 91 |
Number of days that Xuan read at first = 1 u
Number of pages that Xuan read at first
= 1 u x 18
= 18 u
Number of pages that Xuan read in the end = 18 u + 41
Number of days that Xuan read in the end = 1 u + 7
Number of pages that Xuan read in the end
= 13 x (1 u + 7)
= 13 u + 91
18 u + 41 = 13 u + 91
18 u - 13 u = 91 - 41
5 u = 50
1 u = 50 ÷ 5 = 10
Number of days that Xuan read in the end
= 1 u + 7
= 10 + 7
= 17
Answer(s): 17
