The average number of pages Tiffany read in a certain number of days was 12. In the next eight days, Tiffany read another 27 pages. As a result, the average number of pages she read decreased to 9. How many days did Tiffany read in total?
| |
At first |
In the end |
| Number |
1 u |
1 u + 8 |
| Value |
12 |
9 |
| Number x value |
12 u |
9 u + 72 |
Number of days that Tiffany read at first = 1 u
Number of pages that Tiffany read at first
= 1 u x 12
= 12 u
Number of pages that Tiffany read in the end = 12 u + 27
Number of days that Tiffany read in the end = 1 u + 8
Number of pages that Tiffany read in the end
= 9 x (1 u + 8)
= 9 u + 72
12 u + 27 = 9 u + 72
12 u - 9 u = 72 - 27
3 u = 45
1 u = 45 ÷ 3 = 15
Number of days that Tiffany read in the end
= 1 u + 8
= 15 + 8
= 23
Answer(s): 23
