Gwen made croissants for sale. 60% of the croissants were beef croissants and the rest were egg and sardine croissants in the ratio 3 : 1. If a customer bought 80% of the beef croissants and all of the sardine croissants, what percentage of the egg croissants must Gwen sell for her to maintain the original percentage of beef croissants at first? Leave your answer in decimals and correct to 1 decimal place.

Beef croissants	Egg croissants	Sardine croissants
3 u	2 u
	1.5 u	0.5 u

	Beef croissants	Egg croissants	Sardine croissants	Total croissants
Before	3 u	1.5 u	0.5 u	5 u
Change	- 2.4 u	- 1.1 u	- 0.5 u
After	0.6 u	0.4 u	0	1 u

60% = ⁶⁰₁₀₀ = ³₅
80% = ⁸⁰₁₀₀ = ⁴₅

Total number of croissants = 5 u

Number of egg and sardine croissants
= 5 u - 3 u
= 2 u

Number of egg croissants at first
= ³₄ x 2 u
= 1.5 u

Number of sardine croissants at first
= 2 u - 1.5 u
= 0.5 u

Number of beef croissants sold
= 80% x 3 u
= ⁸⁰₁₀₀ x 3 u
= ⁴₅ x 3 u
= 2.4 u

Number of sardine croissants sold
= ¹₄ x 2 u
= 0.5 u

Number of beef croissants left 
= 3 u - 2.4 u
= 0.6 u

To maintain the percentage of the beef croissants in the end, 
60% → 0.6 u
100% → ^0.6₆₀ x 100 = 1 u

Total number of croissants in the end to maintain the original percentage of beef croissants = 1 u

Number of egg croissants left
= 1 u - 0.6 u
= 0.4 u

Number of egg croissants that Gwen must sell to maintain the original percentage of beef croissants
= 1.5 u - 0.4 u
= 1.1 u

Percentage of the egg croissants that Gwen must sell
= ^1.1_1.5 x 100%
= 73.3%

Answer(s): 73.3%