The average number of pages Gem read in a certain number of days was 13. In the next three days, Gem read another 15 pages. As a result, the average number of pages she read decreased to 10. How many days did Gem read in total?
| |
At first |
In the end |
| Number |
1 u |
1 u + 3 |
| Value |
13 |
10 |
| Number x value |
13 u |
10 u + 30 |
Number of days that Gem read at first = 1 u
Number of pages that Gem read at first
= 1 u x 13
= 13 u
Number of pages that Gem read in the end = 13 u + 15
Number of days that Gem read in the end = 1 u + 3
Number of pages that Gem read in the end
= 10 x (1 u + 3)
= 10 u + 30
13 u + 15 = 10 u + 30
13 u - 10 u = 30 - 15
3 u = 15
1 u = 15 ÷ 3 = 5
Number of days that Gem read in the end
= 1 u + 3
= 5 + 3
= 8
Answer(s): 8
