The ratio of the number of cookies in Container J to the number of cookies in Container K was 7 : 3. 10% of the cookies in Container J and 0.9 of those in Container K were vanilla. After transferring the cookies between the 2 boxes, the number of chocolate cookies in both boxes are the same. Likewise, the number of vanilla cookies in both boxes are the same. If a total of 288 cookies were moved, how many more cookies were there in Container J than Container K at first?

Container J		Container K
7 u		3 u
Vanilla	Chocolate	Vanilla	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 vanilla cookies in Container J
= 10% x 7 u
= ¹⁰₁₀₀ x 7 u
= 0.7 u

Number of chocolate cookies in Container J
= 7 u - 0.7 u
= 6.3 u

Number of vanilla cookies in Container K
= 0.9 x 3 u
= 2.7 u

Number of chocolate cookies in Container K
= 3 u - 2.7 u
= 0.3 u

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

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

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

4 u = 288

1 u = 288 ÷ 4 = 72

Number of more cookies in Container J than Container K at first
= 7 u - 3 u
= 4 u
= 4 x 72
= 288

Answer(s): 288