Emily, Kylie and Linda had 720 pens. Kylie won some of the pens from Emily and as a result, Kylie's pens increased by 50%. Linda then won some pens from Kylie and Linda's pens increased by 75%. Finally, Linda lost some of her pens to Emily and Emily's pens increased by 20%. In the end, they realised that they each had an equal number of pens. How many percent less did Emily have in the end than what she had at first? Correct your answer to 1 decimal place.

Emily	Kylie	Linda
720
	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 = 720

1 group = 720 ÷ 3 = 240

1 group = 6 boxes
6 boxes = 240

1 box = 240 ÷ 6 = 40

1 group + 1 box = 7 p
240 + 40 = 7 p
7 p = 280

1 p = 280 ÷ 7 = 40

3 p = 3 x 40 = 120

1 group + 3 p = 3 u
240 + 120 = 3 u
3 u = 360

1 u = 360 ÷ 3 = 120

Number of pens that Emily had at first
= 5 boxes + 1 u
= (5 x 40) + 120
= 200 + 120
= 320

Percent that Emily had less in the end than at first
= ^{320 - 240}₃₂₀ x 100%
≈ 25.0%

Answer(s): 25.0%