The average number of pages Lucy read in a certain number of days was 12. In the next five days, Lucy read another 84 pages. As a result, the average number of pages she read increased to 14. How many days did Lucy read in total?
| |
At first |
In the end |
| Number |
1 u |
1 u + 5 |
| Value |
12 |
14 |
| Number x value |
12 u |
14 u + 70 |
Number of days that Lucy read at first = 1 u
Number of pages that Lucy read at first
= 1 u x 12
= 12 u
Number of pages that Lucy read in the end = 12 u + 84
Number of days that Lucy read in the end = 1 u + 5
Number of pages that Lucy read in the end
= 14 x (1 u + 5)
= 14 u + 70
14 u + 70 = 12 u + 84
14 u - 12 u = 84 - 70
2 u = 14
1 u = 14 ÷ 2 = 7
Number of days that Lucy read in the end
= 1 u + 5
= 7 + 5
= 12
Answer(s): 12
