The average number of pages Shiyun read in a certain number of days was 18. In the next five days, Shiyun read another 50 pages. As a result, the average number of pages she read decreased to 16. How many days did Shiyun read in total?
| |
At first |
In the end |
| Number |
1 u |
1 u + 5 |
| Value |
18 |
16 |
| Number x value |
18 u |
16 u + 80 |
Number of days that Shiyun read at first = 1 u
Number of pages that Shiyun read at first
= 1 u x 18
= 18 u
Number of pages that Shiyun read in the end = 18 u + 50
Number of days that Shiyun read in the end = 1 u + 5
Number of pages that Shiyun read in the end
= 16 x (1 u + 5)
= 16 u + 80
18 u + 50 = 16 u + 80
18 u - 16 u = 80 - 50
2 u = 30
1 u = 30 ÷ 2 = 15
Number of days that Shiyun read in the end
= 1 u + 5
= 15 + 5
= 20
Answer(s): 20
