The ratio of the number of puffs in Container Y to the number of puffs in Container Z was 7 : 3. 20% of the puffs in Container Y and 0.8 of those in Container Z were mocha. After transferring the puffs between the 2 boxes, the number of butter cream puffs in both boxes are the same. Likewise, the number of mocha puffs in both boxes are the same. If a total of 300 puffs were moved, how many more puffs were there in Container Y than Container Z at first?

Container Y		Container Z
7 u		3 u
Mocha	Butter Cream	Mocha	Butter Cream
1.4 u	5.6 u	2.4 u	0.6 u
+ 0.5 u	- 2.5 u	- 0.5 u	+ 2.5 u
1.9 u	3.1 u	1.9 u	3.1 u

Number of mocha puffs in Container Y
= 20% x 7 u
= ²⁰₁₀₀ x 7 u
= 1.4 u

Number of butter cream puffs in Container Y
= 7 u - 1.4 u
= 5.6 u

Number of mocha puffs in Container Z
= 0.8 x 3 u
= 2.4 u

Number of butter cream puffs in Container Z
= 3 u - 2.4 u
= 0.6 u

Number of mocha puffs in each box in the end
= (1.4 u + 2.4 u) ÷ 2
= 3.8 u ÷ 2
= 1.9 u

Number of butter cream puffs in each box in the end
= (5.6 u + 0.6 u) ÷ 2
= 6.2 u ÷ 2
= 3.1 u

Number of puffs moved
= 0.5 u + 2.5 u
= 3 u

3 u = 300

1 u = 300 ÷ 3 = 100

Number of more puffs in Container Y than Container Z at first
= 7 u - 3 u
= 4 u
= 4 x 100
= 400

Answer(s): 400