Irene made buns for sale. 40% of the buns were kaya buns and the rest were curry and sardine buns in the ratio 3 : 1. If a customer bought 65% of the kaya buns and all of the sardine buns, what percentage of the curry buns must Irene sell for her to maintain the original percentage of kaya buns at first? Leave your answer in decimals and correct to 1 decimal place.

Kaya buns	Curry buns	Sardine buns
2 u	3 u
	2.25 u	0.75 u

	Kaya buns	Curry buns	Sardine buns	Total buns
Before	2 u	2.25 u	0.75 u	5 u
Change	- 1.3 u	- 1.2 u	- 0.75 u
After	0.7 u	1.05 u	0	1.75 u

40% = ⁴⁰₁₀₀ = ²₅
65% = ⁶⁵₁₀₀ = ¹³₂₀

Total number of buns = 5 u

Number of curry and sardine buns
= 5 u - 2 u
= 3 u

Number of curry buns at first
= ³₄ x 3 u
= 2.25 u

Number of sardine buns at first
= 3 u - 2.25 u
= 0.75 u

Number of kaya buns sold
= 65% x 2 u
= ⁶⁵₁₀₀ x 2 u
= ¹³₂₀ x 2 u
= 1.3 u

Number of sardine buns sold
= ¹₄ x 3 u
= 0.75 u

Number of kaya buns left 
= 2 u - 1.3 u
= 0.7 u

To maintain the percentage of the kaya buns in the end, 
40% → 0.7 u
100% → ^0.7₄₀ x 100 = 1.75 u

Total number of buns in the end to maintain the original percentage of kaya buns = 1.75 u

Number of curry buns left
= 1.75 u - 0.7 u
= 1.05 u

Number of curry buns that Irene must sell to maintain the original percentage of kaya buns
= 2.25 u - 1.05 u
= 1.2 u

Percentage of the curry buns that Irene must sell
= ^1.2_2.25 x 100%
= 53.3%

Answer(s): 53.3%