Min, Risa and Sabrina had 936 beads. Risa won some of the beads from Min and as a result, Risa's beads increased by 50%. Sabrina then won some beads from Risa and Sabrina's beads increased by 30%. Finally, Sabrina lost some of her beads to Min and Min's beads increased by 20%. In the end, they realised that they each had an equal number of beads. How many percent less did Min have in the end than what she had at first? Correct your answer to 1 decimal place.

Min	Risa	Sabrina
936
	2 u
- 1 u	+ 1 u
	3 u
		10 p
	- 3 p	+ 3 p
		13 p
5 boxes
+ 1 box		- 1 box
6 boxes
1 group	1 group	1 group

50% = ⁵⁰₁₀₀ = ¹₂
30% = ³⁰₁₀₀ = ³₁₀
20% = ²⁰₁₀₀ = ¹₅

Working backwards.

3 groups = 936

1 group = 936 ÷ 3 = 312

1 group = 6 boxes
6 boxes = 312

1 box = 312 ÷ 6 = 52

1 group + 1 box = 13 p
312 + 52 = 13 p
13 p = 364

1 p = 364 ÷ 13 = 28

3 p = 3 x 28 = 84

1 group + 3 p = 3 u
312 + 84 = 3 u
3 u = 396

1 u = 396 ÷ 3 = 132

Number of beads that Min had at first
= 5 boxes + 1 u
= (5 x 52) + 132
= 260 + 132
= 392

Percent that Min had less in the end than at first
= ^{392 - 312}₃₉₂ x 100%
≈ 20.4%

Answer(s): 20.4%