Betty made muffins for sale. 60% of the muffins were kaya muffins and the rest were curry and egg muffins in the ratio 4 : 1. If a customer bought 70% of the kaya muffins and all of the egg muffins, what percentage of the curry muffins must Betty 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	Curry muffins	Egg muffins
3 u	2 u
	1.6 u	0.4 u

	Kaya muffins	Curry muffins	Egg muffins	Total muffins
Before	3 u	1.6 u	0.4 u	5 u
Change	- 2.1 u	- 1 u	- 0.4 u
After	0.9 u	0.6 u	0	1.5 u

60% = ⁶⁰₁₀₀ = ³₅
70% = ⁷⁰₁₀₀ = ⁷₁₀

Total number of muffins = 5 u

Number of curry and egg muffins
= 5 u - 3 u
= 2 u

Number of curry muffins at first
= ⁴₅ x 2 u
= 1.6 u

Number of egg muffins at first
= 2 u - 1.6 u
= 0.4 u

Number of kaya muffins sold
= 70% x 3 u
= ⁷⁰₁₀₀ x 3 u
= ⁷₁₀ x 3 u
= 2.1 u

Number of egg muffins sold
= ¹₅ x 2 u
= 0.4 u

Number of kaya muffins left 
= 3 u - 2.1 u
= 0.9 u

To maintain the percentage of the kaya muffins in the end, 
60% → 0.9 u
100% → ^0.9₆₀ x 100 = 1.5 u

Total number of muffins in the end to maintain the original percentage of kaya muffins = 1.5 u

Number of curry muffins left
= 1.5 u - 0.9 u
= 0.6 u

Number of curry muffins that Betty must sell to maintain the original percentage of kaya muffins
= 1.6 u - 0.6 u
= 1 u

Percentage of the curry muffins that Betty must sell
= ¹_1.6 x 100%
= 62.5%

Answer(s): 62.5%