Risa made muffins for sale. 45% of the muffins were sardine muffins and the rest were curry and beef muffins in the ratio 4 : 1. If a customer bought 70% of the sardine muffins and all of the beef muffins, what percentage of the curry muffins must Risa sell for her to maintain the original percentage of sardine muffins at first? Leave your answer in decimals and correct to 1 decimal place.

Sardine muffins	Curry muffins	Beef muffins
9 u	11 u
	8.8 u	2.2 u

	Sardine muffins	Curry muffins	Beef muffins	Total muffins
Before	9 u	8.8 u	2.2 u	20 u
Change	- 6.3 u	- 5.5 u	- 2.2 u
After	2.7 u	3.3 u	0	6 u

45% = ⁴⁵₁₀₀ = ⁹₂₀
70% = ⁷⁰₁₀₀ = ⁷₁₀

Total number of muffins = 20 u

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

Number of curry muffins at first
= ⁴₅ x 11 u
= 8.8 u

Number of beef muffins at first
= 11 u - 8.8 u
= 2.2 u

Number of sardine muffins sold
= 70% x 9 u
= ⁷⁰₁₀₀ x 9 u
= ⁷₁₀ x 9 u
= 6.3 u

Number of beef muffins sold
= ¹₅ x 11 u
= 2.2 u

Number of sardine muffins left 
= 9 u - 6.3 u
= 2.7 u

To maintain the percentage of the sardine muffins in the end, 
45% → 2.7 u
100% → ^2.7₄₅ x 100 = 6 u

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

Number of curry muffins left
= 6 u - 2.7 u
= 3.3 u

Number of curry muffins that Risa must sell to maintain the original percentage of sardine muffins
= 8.8 u - 3.3 u
= 5.5 u

Percentage of the curry muffins that Risa must sell
= ^5.5_8.8 x 100%
= 62.5%

Answer(s): 62.5%