Justin had three bags of corn starch, V, W and X and the mass of each bag of corn starch was in the ratio 3 : 4 : 5. Justin decided to transfer 40% of corn starch from Bag V into Bag W and 70% of corn starch from Bag X into Bag W. Given that the mass of Bag W was 60.9 kg in the end, how many kilograms of corn starch were transferred into Bag W?

	V	W	X
Before	3 u	4 u	5 u
Change 1	- 1.2 u	+ 1.2 u
Change 2		+ 3.5 u	- 3.5 u
After	1.8 u	8.7 u	1.5 u

Mass of corn starch transferred from Bag V into Bag W
= 40% x 3 u
= ⁴⁰₁₀₀ x 3 u
= 1.8 u

Mass of corn starch transferred from Bag X into Bag W
= 70% x 5 u
= ⁷⁰₁₀₀ x 5 u
= 3.5 u

Mass of corn starch in Bag W in the end
= 4 u + 1.2 u + 3.5 u
= 8.7 u

8.7 u = 60.9 

1 u = 60.9 ÷ 8.7 = 7

Mass of corn starch transferred into Bag W
= 1.2 u + 3.5 u
= 4.7 u
= 4.7 x 7
= 32.9 kg

Answer(s): 32.9 kg