Amelia had 25% more coins than Levi. Sebastian had 50% fewer coins than Amelia. Amelia and Levi gave Sebastian some coins in the ratio of 4 : 5. As a result, Sebastian had 60% more coins than before. Given that Levi had 25 less coins than Sebastian in the end, how many coins did Levi give to Sebastian?

Amelia	Levi	Sebastian
5x2	4x2
2x5		1x5
10	8	5

100% + 25% = 125%
125% = ¹²⁵₁₀₀ = ⁵₄

Amelia : Levi = 5 : 4

100% - 50% = 50%
50% = ⁵⁰₁₀₀ = ¹₂

Amelia : Sebastian = 2 : 1

The number of coins that Amelia had at first is repeated. Make the number of coins that Amelia had at first the same.  LCM of 5 and 2 is 10.

	Amelia	Levi	Sebastian
Before	10x3 =  30 u	8x3 = 24 u	5x3 = 15 u
Change			+ 3x3 = + 9 u
Comparing the changes in the number of coins	- 4x1 = - 4 u	- 5x1 = - 5 u	+ 9x1 = + 9 u
After	26 u	19 u	8x3 = 24 u

60% x 5 
= ⁶⁰₁₀₀ x 5 
= 3 

The total number of coins that Amelia and Levi gave to Sebastian is repeated.  Make the total number of coins that Amelia and Levi gave to Sebastian the same.  LCM of 9 and 3 is 9.

Number of coins that Levi had less than Sebastian 
= 24 u - 19 u
= 5 u

5 u = 25

1 u = 25 ÷ 5 = 5

Number of coins that Levi gave to Sebastian
= 5 u
= 5 x 5
= 25

Answer(s): 25