The average number of pages Penelope read in a certain number of days was 20. In the next five days, Penelope read another 31 pages. As a result, the average number of pages she read decreased to 17. How many days did Penelope read in total?
| |
At first |
In the end |
| Number |
1 u |
1 u + 5 |
| Value |
20 |
17 |
| Number x value |
20 u |
17 u + 85 |
Number of days that Penelope read at first = 1 u
Number of pages that Penelope read at first
= 1 u x 20
= 20 u
Number of pages that Penelope read in the end = 20 u + 31
Number of days that Penelope read in the end = 1 u + 5
Number of pages that Penelope read in the end
= 17 x (1 u + 5)
= 17 u + 85
20 u + 31 = 17 u + 85
20 u - 17 u = 85 - 31
3 u = 54
1 u = 54 ÷ 3 = 18
Number of days that Penelope read in the end
= 1 u + 5
= 18 + 5
= 23
Answer(s): 23
