Xavier has 70% as many stickers as Julian. If Xavier gives away 50% of the stickers and Julian gives away 90% of his stickers, they will have 72 stickers altogether. How many stickers do the two of them have?

	Xavier	Julian	Total
Comparing Xavier and Julian at first	7x2 = 14 u	10x2 = 20 u
Before	2x7 = 14 u	10x2 =  20 u
Change	- 1x7 = - 7 u	- 9x2 = - 18 u
After	1x7 = 7 u	1x2 = 2 u	72

70% = ⁷⁰₁₀₀ = ⁷₁₀

50% = ⁵⁰₁₀₀ = ¹₂ 

90% =⁹⁰₁₀₀ = ⁹₁₀ 

The number of stickers that Xavier has at first is repeated.  Make the number of stickers that Xavier has the same.  LCM of 7 and 2 is 14 u.

The number of stickers that Julian has at first is repeated. Make the number of stickers that Julian has the same. LCM of 10 and 10 is 20 u.

Number of stickers in the end
= 7 u + 2 u
= 9 u

9 u = 72

1 u = 72 ÷ 9 = 8

Total number of stickers that the two of them have
= 14 u + 20 u
= 34 u
= 34 x 8
= 272

Answer(s): 272