The average number of pages Joelle read in a certain number of days was 20. In the next seven days, Joelle read another 10 pages. As a result, the average number of pages she read decreased to 18. How many days did Joelle read in total?
| |
At first |
In the end |
| Number |
1 u |
1 u + 7 |
| Value |
20 |
18 |
| Number x value |
20 u |
18 u + 126 |
Number of days that Joelle read at first = 1 u
Number of pages that Joelle read at first
= 1 u x 20
= 20 u
Number of pages that Joelle read in the end = 20 u + 10
Number of days that Joelle read in the end = 1 u + 7
Number of pages that Joelle read in the end
= 18 x (1 u + 7)
= 18 u + 126
20 u + 10 = 18 u + 126
20 u - 18 u = 126 - 10
2 u = 116
1 u = 116 ÷ 2 = 58
Number of days that Joelle read in the end
= 1 u + 7
= 58 + 7
= 65
Answer(s): 65
