The ratio of the number of wafers in Container D to the number of wafers in Container E was 9 : 5. 30% of the wafers in Container D and 0.7 of those in Container E were mocha. After transferring the wafers between the 2 boxes, the number of strawberry wafers in both boxes are the same. Likewise, the number of mocha wafers in both boxes are the same. If a total of 294 wafers were moved, how many more wafers were there in Container D than Container E at first?

Container D		Container E
9 u		5 u
Mocha	Strawberry	Mocha	Strawberry
2.7 u	6.3 u	3.5 u	1.5 u
+ 0.4 u	- 2.4 u	- 0.4 u	+ 2.4 u
3.1 u	3.9 u	3.1 u	3.9 u

Number of mocha wafers in Container D
= 30% x 9 u
= ³⁰₁₀₀ x 9 u
= 2.7 u

Number of strawberry wafers in Container D
= 9 u - 2.7 u
= 6.3 u

Number of mocha wafers in Container E
= 0.7 x 5 u
= 3.5 u

Number of strawberry wafers in Container E
= 5 u - 3.5 u
= 1.5 u

Number of mocha wafers in each box in the end
= (2.7 u + 3.5 u) ÷ 2
= 6.2 u ÷ 2
= 3.1 u

Number of strawberry wafers in each box in the end
= (6.3 u + 1.5 u) ÷ 2
= 7.8 u ÷ 2
= 3.9 u

Number of wafers moved
= 0.4 u + 2.4 u
= 2.8 u

2.8 u = 294

1 u = 294 ÷ 2.8 = 105

Number of more wafers in Container D than Container E at first
= 9 u - 5 u
= 4 u
= 4 x 105
= 420

Answer(s): 420