Emma, Shiyun and Tammy had 1215 stickers. Shiyun won some of the stickers from Emma and as a result, Shiyun's stickers increased by 50%. Tammy then won some stickers from Shiyun and Tammy's stickers increased by 80%. Finally, Tammy lost some of her stickers to Emma and Emma's stickers increased by 25%. In the end, they realised that they each had an equal number of stickers. How many percent less did Emma have in the end than what she had at first? Correct your answer to 1 decimal place.

Emma	Shiyun	Tammy
1215
	2 u
- 1 u	+ 1 u
	3 u
		5 p
	- 4 p	+ 4 p
		9 p
4 boxes
+ 1 box		- 1 box
5 boxes
1 group	1 group	1 group

50% = ⁵⁰₁₀₀ = ¹₂
80% = ⁸⁰₁₀₀ = ⁴₅
25% = ²⁵₁₀₀ = ¹₄

Working backwards.

3 groups = 1215

1 group = 1215 ÷ 3 = 405

1 group = 5 boxes
5 boxes = 405

1 box = 405 ÷ 5 = 81

1 group + 1 box = 9 p
405 + 81 = 9 p
9 p = 486

1 p = 486 ÷ 9 = 54

4 p = 4 x 54 = 216

1 group + 4 p = 3 u
405 + 216 = 3 u
3 u = 621

1 u = 621 ÷ 3 = 207

Number of stickers that Emma had at first
= 4 boxes + 1 u
= (4 x 81) + 207
= 324 + 207
= 531

Percent that Emma had less in the end than at first
= ^{531 - 405}₅₃₁ x 100%
≈ 23.7%

Answer(s): 23.7%