The average number of pages Sabrina read in a certain number of days was 20. In the next three days, Sabrina read another 34 pages. As a result, the average number of pages she read decreased to 18. How many days did Sabrina read in total?
| |
At first |
In the end |
| Number |
1 u |
1 u + 3 |
| Value |
20 |
18 |
| Number x value |
20 u |
18 u + 54 |
Number of days that Sabrina read at first = 1 u
Number of pages that Sabrina read at first
= 1 u x 20
= 20 u
Number of pages that Sabrina read in the end = 20 u + 34
Number of days that Sabrina read in the end = 1 u + 3
Number of pages that Sabrina read in the end
= 18 x (1 u + 3)
= 18 u + 54
20 u + 34 = 18 u + 54
20 u - 18 u = 54 - 34
2 u = 20
1 u = 20 ÷ 2 = 10
Number of days that Sabrina read in the end
= 1 u + 3
= 10 + 3
= 13
Answer(s): 13
