Esther and Vincent collect marbles and stickers. Vincent has 75 more stickers than marbles. Vincent has 3 times the number of marbles Esther has, and Esther has 40% more stickers than Vincent. After Esther gives Vincent all of her marbles and Vincent gives Esther 60% of his stickers, Vincent has 12 more marbles than stickers. Find the number of stickers Esther has at first.

Esther		Vincent
Stickers	Marbles	Stickers	Marbles
4.2 u + 105	1 u	3 u + 75	3 u
+ 1.8 u + 45	- 1 u	- 1.8 u - 45	+ 1 u
6 u + 150	0	1.2 u + 30	4 u

100% + 40% = 140% 

140% x 3 u
= ¹⁴⁰₁₀₀ x 3 u
= 4.2 u

140% x 75
= ¹⁴⁰₁₀₀ x 75
= 105 

60% x 3 u
= ⁶⁰₁₀₀ x 3 u
= 1.8 u  

60% x 75 
= ⁶⁰₁₀₀ x 75
= 45 

If another 12 stickers are given to Vincent, he will have equal number of stickers and marbles in the end.
4 u = 1.2 u + 30 + 12
4 u - 1.2 u = 42
2.8 u = 42

1 u = 42 ÷ 2.8 = 15

Number of stickers that Esther has at first
= 4.2 u + 105
= 4.2 x 15 + 105
= 63 + 105
= 168
 
Answer(s): 168