Joelle, Irene and Emma had 720 marbles. Irene won some of the marbles from Joelle and as a result, Irene's marbles increased by 25%. Emma then won some marbles from Irene and Emma's marbles increased by 75%. Finally, Emma lost some of her marbles to Joelle and Joelle's marbles increased by 20%. In the end, they realised that they each had an equal number of marbles. How many percent less did Joelle have in the end than what she had at first? Correct your answer to 1 decimal place.

Joelle	Irene	Emma
720
	4 u
- 1 u	+ 1 u
	5 u
		4 p
	- 3 p	+ 3 p
		7 p
5 boxes
+ 1 box		- 1 box
6 boxes
1 group	1 group	1 group

25% = ²⁵₁₀₀ = ¹₄
75% = ⁷⁵₁₀₀ = ³₄
20% = ²⁰₁₀₀ = ¹₅

Working backwards.

3 groups = 720

1 group = 720 ÷ 3 = 240

1 group = 6 boxes
6 boxes = 240

1 box = 240 ÷ 6 = 40

1 group + 1 box = 7 p
240 + 40 = 7 p
7 p = 280

1 p = 280 ÷ 7 = 40

3 p = 3 x 40 = 120

1 group + 3 p = 5 u
240 + 120 = 5 u
5 u = 360

1 u = 360 ÷ 5 = 72

Number of marbles that Joelle had at first
= 5 boxes + 1 u
= (5 x 40) + 72
= 200 + 72
= 272

Percent that Joelle had less in the end than at first
= ^{272 - 240}₂₇₂ x 100%
≈ 11.8%

Answer(s): 11.8%