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

Lotus paste puffs	Beef puffs	Chicken puffs
9 u	11 u
	8.8 u	2.2 u

	Lotus paste puffs	Beef puffs	Chicken puffs	Total puffs
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 puffs = 20 u

Number of beef and chicken puffs
= 20 u - 9 u
= 11 u

Number of beef puffs at first
= ⁴₅ x 11 u
= 8.8 u

Number of chicken puffs at first
= 11 u - 8.8 u
= 2.2 u

Number of lotus paste puffs sold
= 75% x 9 u
= ⁷⁵₁₀₀ x 9 u
= ³₄ x 9 u
= 6.75 u

Number of chicken puffs sold
= ¹₅ x 11 u
= 2.2 u

Number of lotus paste puffs left 
= 9 u - 6.75 u
= 2.25 u

To maintain the percentage of the lotus paste puffs in the end, 
45% → 2.25 u
100% → ^2.25₄₅ x 100 = 5 u

Total number of puffs in the end to maintain the original percentage of lotus paste puffs = 5 u

Number of beef puffs left
= 5 u - 2.25 u
= 2.75 u

Number of beef puffs that Wendy must sell to maintain the original percentage of lotus paste puffs
= 8.8 u - 2.75 u
= 6.05 u

Percentage of the beef puffs that Wendy must sell
= ^6.05_8.8 x 100%
= 68.8%

Answer(s): 68.8%