The ratio of the number of biscuits in Container R to the number of biscuits in Container S was 9 : 5. 40% of the biscuits in Container R and 0.8 of those in Container S were matcha. After transferring the biscuits between the 2 containers, the number of mocha biscuits in both containers are the same. Likewise, the number of matcha biscuits in both containers are the same. If a total of 288 biscuits were moved, how many more biscuits were there in Container R than Container S at first?

Container R		Container S
9 u		5 u
Matcha	Mocha	Matcha	Mocha
3.6 u	5.4 u	4 u	1 u
+ 0.2 u	- 2.2 u	- 0.2 u	+ 2.2 u
3.8 u	3.2 u	3.8 u	3.2 u

Number of matcha biscuits in Container R
= 40% x 9 u
= ⁴⁰₁₀₀ x 9 u
= 3.6 u

Number of mocha biscuits in Container R
= 9 u - 3.6 u
= 5.4 u

Number of matcha biscuits in Container S
= 0.8 x 5 u
= 4 u

Number of mocha biscuits in Container S
= 5 u - 4 u
= 1 u

Number of matcha biscuits in each container in the end
= (3.6 u + 4 u) ÷ 2
= 7.6 u ÷ 2
= 3.8 u

Number of mocha biscuits in each container in the end
= (5.4 u + 1 u) ÷ 2
= 6.4 u ÷ 2
= 3.2 u

Number of biscuits moved
= 0.2 u + 2.2 u
= 2.4 u

2.4 u = 288

1 u = 288 ÷ 2.4 = 120

Number of more biscuits in Container R than Container S at first
= 9 u - 5 u
= 4 u
= 4 x 120
= 480

Answer(s): 480