The average number of pages Gem read in a certain number of days was 17. In the next three days, Gem read another 72 pages. As a result, the average number of pages she read increased to 20. How many days did Gem read in total?
| |
At first |
In the end |
| Number |
1 u |
1 u + 3 |
| Value |
17 |
20 |
| Number x value |
17 u |
20 u + 60 |
Number of days that Gem read at first = 1 u
Number of pages that Gem read at first
= 1 u x 17
= 17 u
Number of pages that Gem read in the end = 17 u + 72
Number of days that Gem read in the end = 1 u + 3
Number of pages that Gem read in the end
= 20 x (1 u + 3)
= 20 u + 60
20 u + 60 = 17 u + 72
20 u - 17 u = 72 - 60
3 u = 12
1 u = 12 ÷ 3 = 4
Number of days that Gem read in the end
= 1 u + 3
= 4 + 3
= 7
Answer(s): 7
