Tammy, Kathy and Natalie had 702 stickers. Kathy won some of the stickers from Tammy and as a result, Kathy's stickers increased by 50%. Natalie then won some stickers from Kathy and Natalie's stickers increased by 40%. Finally, Natalie lost some of her stickers to Tammy and Tammy's stickers increased by 20%. In the end, they realised that they each had an equal number of stickers. How many percent less did Tammy have in the end than what she had at first? Correct your answer to 1 decimal place.

Tammy	Kathy	Natalie
702
	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 = 702

1 group = 702 ÷ 3 = 234

1 group = 6 boxes
6 boxes = 234

1 box = 234 ÷ 6 = 39

1 group + 1 box = 7 p
234 + 39 = 7 p
7 p = 273

1 p = 273 ÷ 7 = 39

2 p = 2 x 39 = 78

1 group + 2 p = 3 u
234 + 78 = 3 u
3 u = 312

1 u = 312 ÷ 3 = 104

Number of stickers that Tammy had at first
= 5 boxes + 1 u
= (5 x 39) + 104
= 195 + 104
= 299

Percent that Tammy had less in the end than at first
= ^{299 - 234}₂₉₉ x 100%
≈ 21.7%

Answer(s): 21.7%