Daniel had three bags of brown rice, A, B and C and the mass of each bag of brown rice was in the ratio 2 : 4 : 5. Daniel decided to transfer 30% of brown rice from Bag A into Bag B and 90% of brown rice from Bag C into Bag B. Given that the mass of Bag B was 72.8 kg in the end, how many kilograms of brown rice were transferred into Bag B?

	A	B	C
Before	2 u	4 u	5 u
Change 1	- 0.6 u	+ 0.6 u
Change 2		+ 4.5 u	- 4.5 u
After	1.4 u	9.1 u	0.5 u

Mass of brown rice transferred from Bag A into Bag B
= 30% x 2 u
= ³⁰₁₀₀ x 2 u
= 1.4 u

Mass of brown rice transferred from Bag C into Bag B
= 90% x 5 u
= ⁹⁰₁₀₀ x 5 u
= 4.5 u

Mass of brown rice in Bag B in the end
= 4 u + 0.6 u + 4.5 u
= 9.1 u

9.1 u = 72.8 

1 u = 72.8 ÷ 9.1 = 8

Mass of brown rice transferred into Bag B
= 0.6 u + 4.5 u
= 5.1 u
= 5.1 x 8
= 40.8 kg

Answer(s): 40.8 kg