Pamela, Esther and Lucy had 1350 stamps. Esther won some of the stamps from Pamela and as a result, Esther's stamps increased by 50%. Lucy then won some stamps from Esther and Lucy's stamps increased by 40%. Finally, Lucy lost some of her stamps to Pamela and Pamela's stamps increased by 20%. In the end, they realised that they each had an equal number of stamps. How many percent less did Pamela have in the end than what she had at first? Correct your answer to 1 decimal place.

Pamela	Esther	Lucy
1350
	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 = 1350

1 group = 1350 ÷ 3 = 450

1 group = 6 boxes
6 boxes = 450

1 box = 450 ÷ 6 = 75

1 group + 1 box = 7 p
450 + 75 = 7 p
7 p = 525

1 p = 525 ÷ 7 = 75

2 p = 2 x 75 = 150

1 group + 2 p = 3 u
450 + 150 = 3 u
3 u = 600

1 u = 600 ÷ 3 = 200

Number of stamps that Pamela had at first
= 5 boxes + 1 u
= (5 x 75) + 200
= 375 + 200
= 575

Percent that Pamela had less in the end than at first
= ^{575 - 450}₅₇₅ x 100%
≈ 21.7%

Answer(s): 21.7%