The average number of pages Erika read in a certain number of days was 19. In the next four days, Erika read another 32 pages. As a result, the average number of pages she read decreased to 17. How many days did Erika read in total?
| |
At first |
In the end |
| Number |
1 u |
1 u + 4 |
| Value |
19 |
17 |
| Number x value |
19 u |
17 u + 68 |
Number of days that Erika read at first = 1 u
Number of pages that Erika read at first
= 1 u x 19
= 19 u
Number of pages that Erika read in the end = 19 u + 32
Number of days that Erika read in the end = 1 u + 4
Number of pages that Erika read in the end
= 17 x (1 u + 4)
= 17 u + 68
19 u + 32 = 17 u + 68
19 u - 17 u = 68 - 32
2 u = 36
1 u = 36 ÷ 2 = 18
Number of days that Erika read in the end
= 1 u + 4
= 18 + 4
= 22
Answer(s): 22
