Elyse made sandwiches for sale. 45% of the sandwiches were beef sandwiches and the rest were curry and egg sandwiches in the ratio 4 : 1. If a customer bought 75% of the beef sandwiches and all of the egg sandwiches, what percentage of the curry sandwiches must Elyse sell for her to maintain the original percentage of beef sandwiches at first? Leave your answer in decimals and correct to 1 decimal place.

Beef sandwiches	Curry sandwiches	Egg sandwiches
9 u	11 u
	8.8 u	2.2 u

	Beef sandwiches	Curry sandwiches	Egg sandwiches	Total sandwiches
Before	9 u	8.8 u	2.2 u	20 u
Change	- 6.75 u	- 6.05 u	- 2.2 u
After	2.25 u	2.75 u	0	5 u

45% = ⁴⁵₁₀₀ = ⁹₂₀
75% = ⁷⁵₁₀₀ = ³₄

Total number of sandwiches = 20 u

Number of curry and egg sandwiches
= 20 u - 9 u
= 11 u

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

Number of egg sandwiches at first
= 11 u - 8.8 u
= 2.2 u

Number of beef sandwiches sold
= 75% x 9 u
= ⁷⁵₁₀₀ x 9 u
= ³₄ x 9 u
= 6.75 u

Number of egg sandwiches sold
= ¹₅ x 11 u
= 2.2 u

Number of beef sandwiches left 
= 9 u - 6.75 u
= 2.25 u

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

Total number of sandwiches in the end to maintain the original percentage of beef sandwiches = 5 u

Number of curry sandwiches left
= 5 u - 2.25 u
= 2.75 u

Number of curry sandwiches that Elyse must sell to maintain the original percentage of beef sandwiches
= 8.8 u - 2.75 u
= 6.05 u

Percentage of the curry sandwiches that Elyse must sell
= ^6.05_8.8 x 100%
= 68.8%

Answer(s): 68.8%