Marion and Michael collect pencils and erasers. Michael has 80 more erasers than pencils. Michael has 4 times the number of pencils Marion has, and Marion has 40% more erasers than Michael. After Marion gives Michael all of her pencils and Michael gives Marion 60% of his erasers, Michael has 36 more pencils than erasers. Find the number of erasers Marion has at first.

Marion		Michael
Erasers	Pencils	Erasers	Pencils
5.6 u + 112	1 u	4 u + 80	4 u
+ 2.4 u + 48	- 1 u	- 2.4 u - 48	+ 1 u
8 u + 160	0	1.6 u + 32	5 u

100% + 40% = 140% 

140% x 4 u
= ¹⁴⁰₁₀₀ x 4 u
= 5.6 u

140% x 80
= ¹⁴⁰₁₀₀ x 80
= 112 

60% x 4 u
= ⁶⁰₁₀₀ x 4 u
= 2.4 u  

60% x 80 
= ⁶⁰₁₀₀ x 80
= 48 

If another 36 erasers are given to Michael, he will have equal number of erasers and pencils in the end.
5 u = 1.6 u + 32 + 36
5 u - 1.6 u = 68
3.4 u = 68

1 u = 68 ÷ 3.4 = 20

Number of erasers that Marion has at first
= 5.6 u + 112
= 5.6 x 20 + 112
= 112 + 112
= 224
 
Answer(s): 224