Dana, Gabby and Pamela had 648 stickers. Gabby won some of the stickers from Dana and as a result, Gabby's stickers increased by 50%. Pamela then won some stickers from Gabby and Pamela's stickers increased by 40%. Finally, Pamela lost some of her stickers to Dana and Dana's stickers increased by 20%. In the end, they realised that they each had an equal number of stickers. How many percent less did Dana have in the end than what she had at first? Correct your answer to 1 decimal place.

Dana	Gabby	Pamela
648
	2 u
- 1 u	+ 1 u
	3 u
		5 p
	- 2 p	+ 2 p
		7 p
5 boxes
+ 1 box		- 1 box
6 boxes
1 group	1 group	1 group

50% = ⁵⁰₁₀₀ = ¹₂
40% = ⁴⁰₁₀₀ = ²₅
20% = ²⁰₁₀₀ = ¹₅

Working backwards.

3 groups = 648

1 group = 648 ÷ 3 = 216

1 group = 6 boxes
6 boxes = 216

1 box = 216 ÷ 6 = 36

1 group + 1 box = 7 p
216 + 36 = 7 p
7 p = 252

1 p = 252 ÷ 7 = 36

2 p = 2 x 36 = 72

1 group + 2 p = 3 u
216 + 72 = 3 u
3 u = 288

1 u = 288 ÷ 3 = 96

Number of stickers that Dana had at first
= 5 boxes + 1 u
= (5 x 36) + 96
= 180 + 96
= 276

Percent that Dana had less in the end than at first
= ^{276 - 216}₂₇₆ x 100%
≈ 21.7%

Answer(s): 21.7%