Gwen and Tina collected seashells. Gwen gave 60% of her seashells to Tina and as a result, Tina's seashells increased by 20%. If Gwen had 18 seashells left, find the number of seashells Tina should give to Gwen in the end so that both had an equal number of seashells.

	Gwen	Tina	Comparing the change in Tina's seashells
Before	5x1 = 5 u		5x3 = 15u
Change	- 3x1 = - 3 u	+ 3x1 = + 3 u	+ 1x3 = + 3 u
After	2x1 = 2 u		6x3 = 18 u

60% = ⁶⁰₁₀₀ = ³₅
20% = ²⁰₁₀₀ = ¹₅

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

2 u = 18

1 u = 18 ÷ 2 = 9

Number of seashells that Tina had more than Gwen in the end
= 18 u - 2 u
= 16 u

Number of seashells that Tina should give to Gwen so that both had an equal number of seashells in the end
= 16 u ÷ 2
= 8 u
= 8 x 9
= 72

Answer(s): 72