The average number of pages Zara read in a certain number of days was 15. In the next seven days, Zara read another 31 pages. As a result, the average number of pages she read decreased to 13. How many days did Zara read in total?
| |
At first |
In the end |
| Number |
1 u |
1 u + 7 |
| Value |
15 |
13 |
| Number x value |
15 u |
13 u + 91 |
Number of days that Zara read at first = 1 u
Number of pages that Zara read at first
= 1 u x 15
= 15 u
Number of pages that Zara read in the end = 15 u + 31
Number of days that Zara read in the end = 1 u + 7
Number of pages that Zara read in the end
= 13 x (1 u + 7)
= 13 u + 91
15 u + 31 = 13 u + 91
15 u - 13 u = 91 - 31
2 u = 60
1 u = 60 ÷ 2 = 30
Number of days that Zara read in the end
= 1 u + 7
= 30 + 7
= 37
Answer(s): 37
