Tom has 10% as many stickers as Warren. If Tom gives away 50% of the stickers and Warren gives away 90% of his stickers, they will have 18 stickers altogether. How many stickers do the two of them have?

	Tom	Warren	Total
Comparing Tom and Warren at first	1x2 = 2 u	10x2 = 20 u
Before	2x1 = 2 u	10x2 =  20 u
Change	- 1x1 = - 1 u	- 9x2 = - 18 u
After	1x1 = 1 u	1x2 = 2 u	18

10% = ¹⁰₁₀₀ = ¹₁₀

50% = ⁵⁰₁₀₀ = ¹₂ 

90% =⁹⁰₁₀₀ = ⁹₁₀ 

The number of stickers that Tom has at first is repeated.  Make the number of stickers that Tom has the same.  LCM of 1 and 2 is 2 u.

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

Number of stickers in the end
= 1 u + 2 u
= 3 u

3 u = 18

1 u = 18 ÷ 3 = 6

Total number of stickers that the two of them have
= 2 u + 20 u
= 22 u
= 22 x 6
= 132

Answer(s): 132