The ratio of the number of wafers in Container A to the number of wafers in Container B was 7 : 3. 30% of the wafers in Container A and 0.9 of those in Container B were mango. After transferring the wafers between the 2 containers, the number of cherry wafers in both containers are the same. Likewise, the number of mango wafers in both containers are the same. If a total of 260 wafers were moved, how many more wafers were there in Container A than Container B at first?

Container A		Container B
7 u		3 u
Mango	Cherry	Mango	Cherry
2.1 u	4.9 u	2.7 u	0.3 u
+ 0.3 u	- 2.3 u	- 0.3 u	+ 2.3 u
2.4 u	2.6 u	2.4 u	2.6 u

Number of mango wafers in Container A
= 30% x 7 u
= ³⁰₁₀₀ x 7 u
= 2.1 u

Number of cherry wafers in Container A
= 7 u - 2.1 u
= 4.9 u

Number of mango wafers in Container B
= 0.9 x 3 u
= 2.7 u

Number of cherry wafers in Container B
= 3 u - 2.7 u
= 0.3 u

Number of mango wafers in each container in the end
= (2.1 u + 2.7 u) ÷ 2
= 4.8 u ÷ 2
= 2.4 u

Number of cherry wafers in each container in the end
= (4.9 u + 0.3 u) ÷ 2
= 5.2 u ÷ 2
= 2.6 u

Number of wafers moved
= 0.3 u + 2.3 u
= 2.6 u

2.6 u = 260

1 u = 260 ÷ 2.6 = 100

Number of more wafers in Container A than Container B at first
= 7 u - 3 u
= 4 u
= 4 x 100
= 400

Answer(s): 400