Jean and Mark collect buttons and stickers. Mark has 50 more stickers than buttons. Mark has 4 times the number of buttons Jean has, and Jean has 20% more stickers than Mark. After Jean gives Mark all of her buttons and Mark gives Jean 70% of his stickers, Mark has 42 more buttons than stickers. Find the number of stickers Jean has at first.

Jean		Mark
Stickers	Buttons	Stickers	Buttons
4.8 u + 60	1 u	4 u + 50	4 u
+ 2.8 u + 35	- 1 u	- 2.8 u - 35	+ 1 u
7.6 u + 95	0	1.2 u + 15	5 u

100% + 20% = 120% 

120% x 4 u
= ¹²⁰₁₀₀ x 4 u
= 4.8 u

120% x 50
= ¹²⁰₁₀₀ x 50
= 60 

70% x 4 u
= ⁷⁰₁₀₀ x 4 u
= 2.8 u  

70% x 50 
= ⁷⁰₁₀₀ x 50
= 35 

If another 42 stickers are given to Mark, he will have equal number of stickers and buttons in the end.
5 u = 1.2 u + 15 + 42
5 u - 1.2 u = 57
3.8 u = 57

1 u = 57 ÷ 3.8 = 15

Number of stickers that Jean has at first
= 4.8 u + 60
= 4.8 x 15 + 60
= 72 + 60
= 132
 
Answer(s): 132