Zoe made puffs for sale. 55% of the puffs were sardine puffs and the rest were chocolate and egg puffs in the ratio 4 : 1. If a customer bought 70% of the sardine puffs and all of the egg puffs, what percentage of the chocolate puffs must Zoe sell for her to maintain the original percentage of sardine puffs at first? Leave your answer in decimals and correct to 1 decimal place.

Sardine puffs	Chocolate puffs	Egg puffs
11 u	9 u
	7.2 u	1.8 u

	Sardine puffs	Chocolate puffs	Egg puffs	Total puffs
Before	11 u	7.2 u	1.8 u	20 u
Change	- 7.7 u	- 4.5 u	- 1.8 u
After	3.3 u	2.7 u	0	6 u

55% = ⁵⁵₁₀₀ = ¹¹₂₀
70% = ⁷⁰₁₀₀ = ⁷₁₀

Total number of puffs = 20 u

Number of chocolate and egg puffs
= 20 u - 11 u
= 9 u

Number of chocolate puffs at first
= ⁴₅ x 9 u
= 7.2 u

Number of egg puffs at first
= 9 u - 7.2 u
= 1.8 u

Number of sardine puffs sold
= 70% x 11 u
= ⁷⁰₁₀₀ x 11 u
= ⁷₁₀ x 11 u
= 7.7 u

Number of egg puffs sold
= ¹₅ x 9 u
= 1.8 u

Number of sardine puffs left 
= 11 u - 7.7 u
= 3.3 u

To maintain the percentage of the sardine puffs in the end, 
55% → 3.3 u
100% → ^3.3₅₅ x 100 = 6 u

Total number of puffs in the end to maintain the original percentage of sardine puffs = 6 u

Number of chocolate puffs left
= 6 u - 3.3 u
= 2.7 u

Number of chocolate puffs that Zoe must sell to maintain the original percentage of sardine puffs
= 7.2 u - 2.7 u
= 4.5 u

Percentage of the chocolate puffs that Zoe must sell
= ^4.5_7.2 x 100%
= 62.5%

Answer(s): 62.5%