Warren, Albert and Chan collected buttons in the ratio of 12 : 10 : 7. After Chan gave ¹₅ to Warren and Albert, Chan had 272 less buttons than Warren. The number of buttons that Albert had increased by 10%. How many buttons did Warren and Chan have in the end?

	Warren	Albert	Chan
Before	12 u	10 u	7 u
Change	+ 0.4 u	+ 1 u	- 1.4 u
After	12.4 u	11 u	5.6 u

Number of buttons that Chan gave to Warren and Albert
= ¹₅ x 7 u
= 1.4 u

Number of buttons that Albert received from Chan
= ¹⁰₁₀₀ x 10 u
= 1 u

Number of buttons that Warren received from Chan
= 1.4 u - 1 u
= 0.4 u

Number of less buttons that Chan had less than Warren
= 12.4 u - 5.6 u 
= 6.8 u

6.8 u = 272

1 u = 272 ÷ 6.8 = 40

Number of buttons that Warren and Chan had
= 12.4 u + 5.6 u
= 18 u
= 18 x 40
= 720

Answer(s): 720