Emily and Vaidev collect cards and buttons. Vaidev has 64 more buttons than cards. Vaidev has 3 times the number of cards Emily has, and Emily has 25% more buttons than Vaidev. After Emily gives Vaidev all of her cards and Vaidev gives Emily 75% of his buttons, Vaidev has 36 more cards than buttons. Find the number of buttons Emily has at first.

Emily		Vaidev
Buttons	Cards	Buttons	Cards
3.75 u + 80	1 u	3 u + 64	3 u
+ 2.25 u + 48	- 1 u	- 2.25 u - 48	+ 1 u
6 u + 128	0	0.75 u + 16	4 u

100% + 25% = 125% 

125% x 3 u
= ¹²⁵₁₀₀ x 3 u
= 3.75 u

125% x 64
= ¹²⁵₁₀₀ x 64
= 80 

75% x 3 u
= ⁷⁵₁₀₀ x 3 u
= 2.25 u  

75% x 64 
= ⁷⁵₁₀₀ x 64
= 48 

If another 36 buttons are given to Vaidev, he will have equal number of buttons and cards in the end.
4 u = 0.75 u + 16 + 36
4 u - 0.75 u = 52
3.25 u = 52

1 u = 52 ÷ 3.25 = 16

Number of buttons that Emily has at first
= 3.75 u + 80
= 3.75 x 16 + 80
= 60 + 80
= 140
 
Answer(s): 140