Hazel, Xuan and Tammy had 972 stamps. Xuan won some of the stamps from Hazel and as a result, Xuan's stamps increased by 50%. Tammy then won some stamps from Xuan and Tammy's stamps increased by 40%. Finally, Tammy lost some of her stamps to Hazel and Hazel's stamps increased by 20%. In the end, they realised that they each had an equal number of stamps. How many percent less did Hazel have in the end than what she had at first? Correct your answer to 1 decimal place.

Hazel	Xuan	Tammy
972
	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 = 972

1 group = 972 ÷ 3 = 324

1 group = 6 boxes
6 boxes = 324

1 box = 324 ÷ 6 = 54

1 group + 1 box = 7 p
324 + 54 = 7 p
7 p = 378

1 p = 378 ÷ 7 = 54

2 p = 2 x 54 = 108

1 group + 2 p = 3 u
324 + 108 = 3 u
3 u = 432

1 u = 432 ÷ 3 = 144

Number of stamps that Hazel had at first
= 5 boxes + 1 u
= (5 x 54) + 144
= 270 + 144
= 414

Percent that Hazel had less in the end than at first
= ^{414 - 324}₄₁₄ x 100%
≈ 21.7%

Answer(s): 21.7%