Eva made buns for sale. 55% of the buns were beef buns and the rest were egg and chocolate buns in the ratio 3 : 1. If a customer bought 65% of the beef buns and all of the chocolate buns, what percentage of the egg buns must Eva sell for her to maintain the original percentage of beef buns at first? Leave your answer in decimals and correct to 1 decimal place.

Beef buns	Egg buns	Chocolate buns
11 u	9 u
	6.75 u	2.25 u

	Beef buns	Egg buns	Chocolate buns	Total buns
Before	11 u	6.75 u	2.25 u	20 u
Change	- 7.15 u	- 3.6 u	- 2.25 u
After	3.85 u	3.15 u	0	7 u

55% = ⁵⁵₁₀₀ = ¹¹₂₀
65% = ⁶⁵₁₀₀ = ¹³₂₀

Total number of buns = 20 u

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

Number of egg buns at first
= ³₄ x 9 u
= 6.75 u

Number of chocolate buns at first
= 9 u - 6.75 u
= 2.25 u

Number of beef buns sold
= 65% x 11 u
= ⁶⁵₁₀₀ x 11 u
= ¹³₂₀ x 11 u
= 7.15 u

Number of chocolate buns sold
= ¹₄ x 9 u
= 2.25 u

Number of beef buns left 
= 11 u - 7.15 u
= 3.85 u

To maintain the percentage of the beef buns in the end, 
55% → 3.85 u
100% → ^3.85₅₅ x 100 = 7 u

Total number of buns in the end to maintain the original percentage of beef buns = 7 u

Number of egg buns left
= 7 u - 3.85 u
= 3.15 u

Number of egg buns that Eva must sell to maintain the original percentage of beef buns
= 6.75 u - 3.15 u
= 3.6 u

Percentage of the egg buns that Eva must sell
= ^3.6_6.75 x 100%
= 53.3%

Answer(s): 53.3%