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

	Mary	Cindy	Comparing the change in Cindy's seashells
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 seashells that Cindy had is repeated.  Make the increase in the number of seashells that Cindy had the same. LCM of 1 and 3 = 3

9 u = 108

1 u = 108 ÷ 9 = 12

Number of seashells that Cindy had more than Mary in the end
= 13 u - 9 u
= 4 u

Number of seashells that Cindy should give to Mary so that both had an equal number of seashells in the end
= 4 u ÷ 2
= 2 u
= 2 x 12
= 24

Answer(s): 24