Sarah and Erika have some files in the ratio 5 : 13. Sarah has 56 less files than Erika. How many files must Erika give to Sarah so that they will have the same number of files?
| |
Sarah |
Erika |
Total |
| Before |
5 u |
13 u |
18 u |
| Change |
+ 4 u |
- 4 u |
|
After |
1x9 =
9 u |
1x9 =
9 u |
2x9 =
18 u |
The total number of files remains unchanged. Make the total number of files at first and in the end the same. LCM of 2 and 18 is 18.
Difference in the number of files at first
= 13 u - 5 u
= 8 u
8 u = 56
1 u = 56 ÷ 8 = 7
Number of files that each of them had in the end
= 18 u ÷ 2
= 9 u
Number of files that Erika must give to Sarah
= 9 u - 5 u
= 4 u
= 4 x 7
= 28
Answer(s): 28
