Lucy, Linda and Gillian had 936 stamps. Linda won some of the stamps from Lucy and as a result, Linda's stamps increased by 50%. Gillian then won some stamps from Linda and Gillian's stamps increased by 30%. Finally, Gillian lost some of her stamps to Lucy and Lucy's stamps increased by 20%. In the end, they realised that they each had an equal number of stamps. How many percent less did Lucy have in the end than what she had at first? Correct your answer to 1 decimal place.

Lucy	Linda	Gillian
936
	2 u
- 1 u	+ 1 u
	3 u
		10 p
	- 3 p	+ 3 p
		13 p
5 boxes
+ 1 box		- 1 box
6 boxes
1 group	1 group	1 group

50% = ⁵⁰₁₀₀ = ¹₂
30% = ³⁰₁₀₀ = ³₁₀
20% = ²⁰₁₀₀ = ¹₅

Working backwards.

3 groups = 936

1 group = 936 ÷ 3 = 312

1 group = 6 boxes
6 boxes = 312

1 box = 312 ÷ 6 = 52

1 group + 1 box = 13 p
312 + 52 = 13 p
13 p = 364

1 p = 364 ÷ 13 = 28

3 p = 3 x 28 = 84

1 group + 3 p = 3 u
312 + 84 = 3 u
3 u = 396

1 u = 396 ÷ 3 = 132

Number of stamps that Lucy had at first
= 5 boxes + 1 u
= (5 x 52) + 132
= 260 + 132
= 392

Percent that Lucy had less in the end than at first
= ^{392 - 312}₃₉₂ x 100%
≈ 20.4%

Answer(s): 20.4%