The average number of pages Jade read in a certain number of days was 18. In the next five days, Jade read another 36 pages. As a result, the average number of pages she read decreased to 15. How many days did Jade read in total?
| |
At first |
In the end |
| Number |
1 u |
1 u + 5 |
| Value |
18 |
15 |
| Number x value |
18 u |
15 u + 75 |
Number of days that Jade read at first = 1 u
Number of pages that Jade read at first
= 1 u x 18
= 18 u
Number of pages that Jade read in the end = 18 u + 36
Number of days that Jade read in the end = 1 u + 5
Number of pages that Jade read in the end
= 15 x (1 u + 5)
= 15 u + 75
18 u + 36 = 15 u + 75
18 u - 15 u = 75 - 36
3 u = 39
1 u = 39 ÷ 3 = 13
Number of days that Jade read in the end
= 1 u + 5
= 13 + 5
= 18
Answer(s): 18
