Julian had three bags of potato starch, V, W and X and the mass of each bag of potato starch was in the ratio 2 : 1 : 3. Julian decided to transfer 10% of potato starch from Bag V into Bag W and 60% of potato starch from Bag X into Bag W. Given that the mass of Bag W was 18 kg in the end, how many kilograms of potato starch were transferred into Bag W?

	V	W	X
Before	2 u	1 u	3 u
Change 1	- 0.2 u	+ 0.2 u
Change 2		+ 1.8 u	- 1.8 u
After	1.8 u	3 u	1.2 u

Mass of potato starch transferred from Bag V into Bag W
= 10% x 2 u
= ¹⁰₁₀₀ x 2 u
= 1.8 u

Mass of potato starch transferred from Bag X into Bag W
= 60% x 3 u
= ⁶⁰₁₀₀ x 3 u
= 1.8 u

Mass of potato starch in Bag W in the end
= 1 u + 0.2 u + 1.8 u
= 3 u

3 u = 18 

1 u = 18 ÷ 3 = 6

Mass of potato starch transferred into Bag W
= 0.2 u + 1.8 u
= 2 u
= 2 x 6
= 12 kg

Answer(s): 12 kg