Tiffany made muffins for sale. 45% of the muffins were kaya muffins and the rest were beef and chocolate muffins in the ratio 3 : 1. If a customer bought 75% of the kaya muffins and all of the chocolate muffins, what percentage of the beef muffins must Tiffany sell for her to maintain the original percentage of kaya muffins at first? Leave your answer in decimals and correct to 1 decimal place.

Kaya muffins	Beef muffins	Chocolate muffins
9 u	11 u
	8.25 u	2.75 u

	Kaya muffins	Beef muffins	Chocolate muffins	Total muffins
Before	9 u	8.25 u	2.75 u	20 u
Change	- 6.75 u	- 5.5 u	- 2.75 u
After	2.25 u	2.75 u	0	5 u

45% = ⁴⁵₁₀₀ = ⁹₂₀
75% = ⁷⁵₁₀₀ = ³₄

Total number of muffins = 20 u

Number of beef and chocolate muffins
= 20 u - 9 u
= 11 u

Number of beef muffins at first
= ³₄ x 11 u
= 8.25 u

Number of chocolate muffins at first
= 11 u - 8.25 u
= 2.75 u

Number of kaya muffins sold
= 75% x 9 u
= ⁷⁵₁₀₀ x 9 u
= ³₄ x 9 u
= 6.75 u

Number of chocolate muffins sold
= ¹₄ x 11 u
= 2.75 u

Number of kaya muffins left 
= 9 u - 6.75 u
= 2.25 u

To maintain the percentage of the kaya muffins in the end, 
45% → 2.25 u
100% → ^2.25₄₅ x 100 = 5 u

Total number of muffins in the end to maintain the original percentage of kaya muffins = 5 u

Number of beef muffins left
= 5 u - 2.25 u
= 2.75 u

Number of beef muffins that Tiffany must sell to maintain the original percentage of kaya muffins
= 8.25 u - 2.75 u
= 5.5 u

Percentage of the beef muffins that Tiffany must sell
= ^5.5_8.25 x 100%
= 66.7%

Answer(s): 66.7%