Jaslyn and Carl collect pencils and erasers. Carl has 65 less pencils than erasers. Carl has 4 times the number of pencils Jaslyn has, and Jaslyn has 20% more erasers than Carl. After Jaslyn gives Carl all of her pencils and Carl gives Jaslyn 60% of his erasers, Carl has 42 less erasers than pencils. Find the number of erasers Jaslyn has at first.

Jaslyn		Carl
Erasers	Pencils	Erasers	Pencils
4.8 u + 78	1 u	4 u + 65	4 u
+ 2.4 u + 39	- 1 u	- 2.4 u - 39	+ 1 u
7.2 u + 117	0	1.6 u + 26	5 u

100%+ 20% = 120% 

120% x 4 u
= ¹²⁰₁₀₀ x 4 u
= 4.8 u

120% x 65
= ¹²⁰₁₀₀ x 65
= 78 

60% x 4 u
= ⁶⁰₁₀₀ x 4 u
= 2.4 u  

60% x 65 
= ⁶⁰₁₀₀ x 65
= 39 

If another 42 erasers are given to Carl, he will have equal number of erasers and pencils in the end.
5 u = 1.6 u + 26 + 42
5 u - 1.6 u = 68
3.4 u = 68

1 u = 68 ÷ 3.4 = 20

Number of erasers that Jaslyn has at first
= 4.8 u + 78
= 4.8 x 20 + 78
= 96 + 78
= 174
 
Answer(s): 174