Hazel and Cathy have some notebooks in the ratio 3 : 7. Hazel has 72 less notebooks than Cathy. How many notebooks must Cathy give to Hazel so that they will have the same number of notebooks?
| |
Hazel |
Cathy |
Total |
| Before |
3 u |
7 u |
10 u |
| Change |
+ 2 u |
- 2 u |
|
After |
1x5 =
5 u |
1x5 =
5 u |
2x5 =
10 u |
The total number of notebooks remains unchanged. Make the total number of notebooks at first and in the end the same. LCM of 2 and 10 is 10.
Difference in the number of notebooks at first
= 7 u - 3 u
= 4 u
4 u = 72
1 u = 72 ÷ 4 = 18
Number of notebooks that each of them had in the end
= 10 u ÷ 2
= 5 u
Number of notebooks that Cathy must give to Hazel
= 5 u - 3 u
= 2 u
= 2 x 18
= 36
Answer(s): 36
