Tiffany and Ben collect pens and stickers. Ben has 100 less pens than stickers. Ben has 2 times the number of pens Tiffany has, and Tiffany has 20% more stickers than Ben. After Tiffany gives Ben all of her pens and Ben gives Tiffany 70% of his stickers, Ben has 18 less stickers than pens. Find the number of stickers Tiffany has at first.

Tiffany		Ben
Stickers	Pens	Stickers	Pens
2.4 u + 120	1 u	2 u + 100	2 u
+ 1.4 u + 70	- 1 u	- 1.4 u - 70	+ 1 u
3.8 u + 190	0	0.6 u + 30	3 u

100%+ 20% = 120% 

120% x 2 u
= ¹²⁰₁₀₀ x 2 u
= 2.4 u

120% x 100
= ¹²⁰₁₀₀ x 100
= 120 

70% x 2 u
= ⁷⁰₁₀₀ x 2 u
= 1.4 u  

70% x 100 
= ⁷⁰₁₀₀ x 100
= 70 

If another 18 stickers are given to Ben, he will have equal number of stickers and pens in the end.
3 u = 0.6 u + 30 + 18
3 u - 0.6 u = 48
2.4 u = 48

1 u = 48 ÷ 2.4 = 20

Number of stickers that Tiffany has at first
= 2.4 u + 120
= 2.4 x 20 + 120
= 48 + 120
= 168
 
Answer(s): 168