The average number of pages Anna read in a certain number of days was 16. In the next three days, Anna read another 12 pages. As a result, the average number of pages she read decreased to 13. How many days did Anna read in total?
| |
At first |
In the end |
| Number |
1 u |
1 u + 3 |
| Value |
16 |
13 |
| Number x value |
16 u |
13 u + 39 |
Number of days that Anna read at first = 1 u
Number of pages that Anna read at first
= 1 u x 16
= 16 u
Number of pages that Anna read in the end = 16 u + 12
Number of days that Anna read in the end = 1 u + 3
Number of pages that Anna read in the end
= 13 x (1 u + 3)
= 13 u + 39
16 u + 12 = 13 u + 39
16 u - 13 u = 39 - 12
3 u = 27
1 u = 27 ÷ 3 = 9
Number of days that Anna read in the end
= 1 u + 3
= 9 + 3
= 12
Answer(s): 12
