Natalie, Opal and Shannon had 810 stamps. Opal won some of the stamps from Natalie and as a result, Opal's stamps increased by 50%. Shannon then won some stamps from Opal and Shannon's stamps increased by 75%. Finally, Shannon lost some of her stamps to Natalie and Natalie's stamps increased by 20%. In the end, they realised that they each had an equal number of stamps. How many percent less did Natalie have in the end than what she had at first? Correct your answer to 1 decimal place.

Natalie	Opal	Shannon
810
	2 u
- 1 u	+ 1 u
	3 u
		4 p
	- 3 p	+ 3 p
		7 p
5 boxes
+ 1 box		- 1 box
6 boxes
1 group	1 group	1 group

50% = ⁵⁰₁₀₀ = ¹₂
75% = ⁷⁵₁₀₀ = ³₄
20% = ²⁰₁₀₀ = ¹₅

Working backwards.

3 groups = 810

1 group = 810 ÷ 3 = 270

1 group = 6 boxes
6 boxes = 270

1 box = 270 ÷ 6 = 45

1 group + 1 box = 7 p
270 + 45 = 7 p
7 p = 315

1 p = 315 ÷ 7 = 45

3 p = 3 x 45 = 135

1 group + 3 p = 3 u
270 + 135 = 3 u
3 u = 405

1 u = 405 ÷ 3 = 135

Number of stamps that Natalie had at first
= 5 boxes + 1 u
= (5 x 45) + 135
= 225 + 135
= 360

Percent that Natalie had less in the end than at first
= ^{360 - 270}₃₆₀ x 100%
≈ 25.0%

Answer(s): 25.0%