The average number of pages Opal read in a certain number of days was 17. In the next four days, Opal read another 28 pages. As a result, the average number of pages she read decreased to 13. How many days did Opal read in total?
| |
At first |
In the end |
| Number |
1 u |
1 u + 4 |
| Value |
17 |
13 |
| Number x value |
17 u |
13 u + 52 |
Number of days that Opal read at first = 1 u
Number of pages that Opal read at first
= 1 u x 17
= 17 u
Number of pages that Opal read in the end = 17 u + 28
Number of days that Opal read in the end = 1 u + 4
Number of pages that Opal read in the end
= 13 x (1 u + 4)
= 13 u + 52
17 u + 28 = 13 u + 52
17 u - 13 u = 52 - 28
4 u = 24
1 u = 24 ÷ 4 = 6
Number of days that Opal read in the end
= 1 u + 4
= 6 + 4
= 10
Answer(s): 10
