Riordan, Jenson and Colin collected stamps in the ratio of 9 : 5 : 9. After Colin gave ⁴₅ to Riordan and Jenson, Colin had 536 less stamps than Riordan. The number of stamps that Jenson had increased by 20%. How many stamps did Riordan and Colin have in the end?

	Riordan	Jenson	Colin
Before	9 u	5 u	9 u
Change	+ 6.2 u	+ 1 u	- 7.2 u
After	15.2 u	6 u	1.8 u

Number of stamps that Colin gave to Riordan and Jenson
= ⁴₅ x 9 u
= 7.2 u

Number of stamps that Jenson received from Colin
= ²⁰₁₀₀ x 5 u
= 1 u

Number of stamps that Riordan received from Colin
= 7.2 u - 1 u
= 6.2 u

Number of less stamps that Colin had less than Riordan
= 15.2 u - 1.8 u 
= 13.4 u

13.4 u = 536

1 u = 536 ÷ 13.4 = 40

Number of stamps that Riordan and Colin had
= 15.2 u + 1.8 u
= 17 u
= 17 x 40
= 680

Answer(s): 680