The ratio of the number of wafers in Container N to the number of wafers in Container P was 7 : 3. 10% of the wafers in Container N and 0.9 of those in Container P were peach. After transferring the wafers between the 2 boxes, the number of vanilla wafers in both boxes are the same. Likewise, the number of peach wafers in both boxes are the same. If a total of 168 wafers were moved, how many more wafers were there in Container N than Container P at first?

Container N		Container P
7 u		3 u
Peach	Vanilla	Peach	Vanilla
0.7 u	6.3 u	2.7 u	0.3 u
+ 1 u	- 3 u	- 1 u	+ 3 u
1.7 u	3.3 u	1.7 u	3.3 u

Number of peach wafers in Container N
= 10% x 7 u
= ¹⁰₁₀₀ x 7 u
= 0.7 u

Number of vanilla wafers in Container N
= 7 u - 0.7 u
= 6.3 u

Number of peach wafers in Container P
= 0.9 x 3 u
= 2.7 u

Number of vanilla wafers in Container P
= 3 u - 2.7 u
= 0.3 u

Number of peach wafers in each box in the end
= (0.7 u + 2.7 u) ÷ 2
= 3.4 u ÷ 2
= 1.7 u

Number of vanilla wafers in each box in the end
= (6.3 u + 0.3 u) ÷ 2
= 6.6 u ÷ 2
= 3.3 u

Number of wafers moved
= 1 u + 3 u
= 4 u

4 u = 168

1 u = 168 ÷ 4 = 42

Number of more wafers in Container N than Container P at first
= 7 u - 3 u
= 4 u
= 4 x 42
= 168

Answer(s): 168