Gillian made sandwiches for sale. 40% of the sandwiches were sardine sandwiches and the rest were kaya and egg sandwiches in the ratio 3 : 2. If a customer bought 60% of the sardine sandwiches and all of the egg sandwiches, what percentage of the kaya sandwiches must Gillian sell for her to maintain the original percentage of sardine sandwiches at first? Leave your answer in decimals and correct to 1 decimal place.

Sardine sandwiches	Kaya sandwiches	Egg sandwiches
2 u	3 u
	1.8 u	1.2 u

	Sardine sandwiches	Kaya sandwiches	Egg sandwiches	Total sandwiches
Before	2 u	1.8 u	1.2 u	5 u
Change	- 1.2 u	- 0.6 u	- 1.2 u
After	0.8 u	1.2 u	0	2 u

40% = ⁴⁰₁₀₀ = ²₅
60% = ⁶⁰₁₀₀ = ³₅

Total number of sandwiches = 5 u

Number of kaya and egg sandwiches
= 5 u - 2 u
= 3 u

Number of kaya sandwiches at first
= ³₅ x 3 u
= 1.8 u

Number of egg sandwiches at first
= 3 u - 1.8 u
= 1.2 u

Number of sardine sandwiches sold
= 60% x 2 u
= ⁶⁰₁₀₀ x 2 u
= ³₅ x 2 u
= 1.2 u

Number of egg sandwiches sold
= ²₅ x 3 u
= 1.2 u

Number of sardine sandwiches left 
= 2 u - 1.2 u
= 0.8 u

To maintain the percentage of the sardine sandwiches in the end, 
40% → 0.8 u
100% → ^0.8₄₀ x 100 = 2 u

Total number of sandwiches in the end to maintain the original percentage of sardine sandwiches = 2 u

Number of kaya sandwiches left
= 2 u - 0.8 u
= 1.2 u

Number of kaya sandwiches that Gillian must sell to maintain the original percentage of sardine sandwiches
= 1.8 u - 1.2 u
= 0.6 u

Percentage of the kaya sandwiches that Gillian must sell
= ^0.6_1.8 x 100%
= 33.3%

Answer(s): 33.3%