Ivory made buns for sale. 60% of the buns were sardine buns and the rest were mushroom and curry buns in the ratio 3 : 1. If a customer bought 65% of the sardine buns and all of the curry buns, what percentage of the mushroom buns must Ivory sell for her to maintain the original percentage of sardine buns at first? Leave your answer in decimals and correct to 1 decimal place.

Sardine buns	Mushroom buns	Curry buns
3 u	2 u
	1.5 u	0.5 u

	Sardine buns	Mushroom buns	Curry buns	Total buns
Before	3 u	1.5 u	0.5 u	5 u
Change	- 1.95 u	- 0.8 u	- 0.5 u
After	1.05 u	0.7 u	0	1.75 u

60% = ⁶⁰₁₀₀ = ³₅
65% = ⁶⁵₁₀₀ = ¹³₂₀

Total number of buns = 5 u

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

Number of mushroom buns at first
= ³₄ x 2 u
= 1.5 u

Number of curry buns at first
= 2 u - 1.5 u
= 0.5 u

Number of sardine buns sold
= 65% x 3 u
= ⁶⁵₁₀₀ x 3 u
= ¹³₂₀ x 3 u
= 1.95 u

Number of curry buns sold
= ¹₄ x 2 u
= 0.5 u

Number of sardine buns left 
= 3 u - 1.95 u
= 1.05 u

To maintain the percentage of the sardine buns in the end, 
60% → 1.05 u
100% → ^1.05₆₀ x 100 = 1.75 u

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

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

Number of mushroom buns that Ivory must sell to maintain the original percentage of sardine buns
= 1.5 u - 0.7 u
= 0.8 u

Percentage of the mushroom buns that Ivory must sell
= ^0.8_1.5 x 100%
= 53.3%

Answer(s): 53.3%