Eva, Emily and Yoko had 945 stamps. Emily won some of the stamps from Eva and as a result, Emily's stamps increased by 50%. Yoko then won some stamps from Emily and Yoko's stamps increased by 80%. Finally, Yoko lost some of her stamps to Eva and Eva's stamps increased by 25%. In the end, they realised that they each had an equal number of stamps. How many percent less did Eva have in the end than what she had at first? Correct your answer to 1 decimal place.

Eva	Emily	Yoko
945
	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 = 945

1 group = 945 ÷ 3 = 315

1 group = 5 boxes
5 boxes = 315

1 box = 315 ÷ 5 = 63

1 group + 1 box = 9 p
315 + 63 = 9 p
9 p = 378

1 p = 378 ÷ 9 = 42

4 p = 4 x 42 = 168

1 group + 4 p = 3 u
315 + 168 = 3 u
3 u = 483

1 u = 483 ÷ 3 = 161

Number of stamps that Eva had at first
= 4 boxes + 1 u
= (4 x 63) + 161
= 252 + 161
= 413

Percent that Eva had less in the end than at first
= ^{413 - 315}₄₁₃ x 100%
≈ 23.7%

Answer(s): 23.7%