Emma and Opal collected buttons. Emma gave 25% of her buttons to Opal and as a result, Opal's buttons increased by 30%. If Emma had 108 buttons left, find the number of buttons Opal should give to Emma in the end so that both had an equal number of buttons.

	Emma	Opal	Comparing the change in Opal's buttons
Before	4x3 = 12 u		10x1 = 10u
Change	- 1x3 = - 3 u	+ 1x3 = + 3 u	+ 3x1 = + 3 u
After	3x3 = 9 u		13x1 = 13 u

25% = ²⁵₁₀₀ = ¹₄
30% = ³⁰₁₀₀ = ³₁₀

The increase in the number of buttons that Opal had is repeated.  Make the increase in the number of buttons that Opal had the same. LCM of 1 and 3 = 3

9 u = 108

1 u = 108 ÷ 9 = 12

Number of buttons that Opal had more than Emma in the end
= 13 u - 9 u
= 4 u

Number of buttons that Opal should give to Emma so that both had an equal number of buttons in the end
= 4 u ÷ 2
= 2 u
= 2 x 12
= 24

Answer(s): 24