The ratio of the number of puffs in Container L to the number of puffs in Container M was 9 : 5. 20% of the puffs in Container L and 0.8 of those in Container M were butter cream. After transferring the puffs between the 2 boxes, the number of strawberry puffs in both boxes are the same. Likewise, the number of butter cream puffs in both boxes are the same. If a total of 210 puffs were moved, how many more puffs were there in Container L than Container M at first?

Container L		Container M
9 u		5 u
Butter Cream	Strawberry	Butter Cream	Strawberry
1.8 u	7.2 u	4 u	1 u
+ 1.1 u	- 3.1 u	- 1.1 u	+ 3.1 u
2.9 u	4.1 u	2.9 u	4.1 u

Number of butter cream puffs in Container L
= 20% x 9 u
= ²⁰₁₀₀ x 9 u
= 1.8 u

Number of strawberry puffs in Container L
= 9 u - 1.8 u
= 7.2 u

Number of butter cream puffs in Container M
= 0.8 x 5 u
= 4 u

Number of strawberry puffs in Container M
= 5 u - 4 u
= 1 u

Number of butter cream puffs in each box in the end
= (1.8 u + 4 u) ÷ 2
= 5.8 u ÷ 2
= 2.9 u

Number of strawberry puffs in each box in the end
= (7.2 u + 1 u) ÷ 2
= 8.2 u ÷ 2
= 4.1 u

Number of puffs moved
= 1.1 u + 3.1 u
= 4.2 u

4.2 u = 210

1 u = 210 ÷ 4.2 = 50

Number of more puffs in Container L than Container M at first
= 9 u - 5 u
= 4 u
= 4 x 50
= 200

Answer(s): 200