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

Container W		Container X
7 u		3 u
Cherry	Chocolate	Cherry	Chocolate
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 cherry biscuits in Container W
= 10% x 7 u
= ¹⁰₁₀₀ x 7 u
= 0.7 u

Number of chocolate biscuits in Container W
= 7 u - 0.7 u
= 6.3 u

Number of cherry biscuits in Container X
= 0.9 x 3 u
= 2.7 u

Number of chocolate biscuits in Container X
= 3 u - 2.7 u
= 0.3 u

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

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

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

4 u = 168

1 u = 168 ÷ 4 = 42

Number of more biscuits in Container W than Container X at first
= 7 u - 3 u
= 4 u
= 4 x 42
= 168

Answer(s): 168