In March, Zara and Bryan had stamps in the ratio 7 : 3. In April, each of them gave away the same number of stamps. Zara then had four times as many stamps as Bryan.

1. Find the ratio of the number of stamps Bryan had in March to the number of stamps he had in April.
2. Find the ratio of the total number of stamps both had in March to the total number of stamps both had in April.

	Zara	Bryan	Difference
Before	7x3 = 21 u	3x3 = 9 u	4x3 = 12 u
Change	- 5 u	- 5 u
After	4x4 = 16 u	1x4 = 4 u	3x4 = 12 u

(a)
Since Zara and Bryan gave away the same number of stamps, the difference in the number of stamps between Zara and Bryan at first and in the end remains the same.

Make the difference in the number of stamps at first and in the end the same. LCM of 4 and 3 is 12.

Bryan's stamps in March : Bryan's stamps in April
9 : 4

(b)
Total number of stamps in March
= 21 u + 9 u
= 30 u

Total number of stamps in April
= 16 u + 4 u
= 20 u

Total stamps in March : Total stamps in April
30 : 20 _(÷10)
3 : 2 

Answer(s): (a) 9 : 4; (b) 3 : 2