<PRE><B>Question 255570</B>
It is required to make 12 grams of certain chemical compound called Z. This is made from compounds W, X, and Y in the ratio of 2:1:3. The compound Y is itself made from W and X. To make 6 grams of Y requires 4 grams of W and 2 grams of X.
The ratio W:X:Y = 2:1:3
          W:X:Y = 4:2:6
But 6 grams of Y  contains 4 grams of W and 2 grams of X.
Therefore 6 grams of Y can be replaced by 4 grams of W and 
2 grams of X. 
Therefore 12 grams of Z contains 4+4 = 8 grams of W
And 12 grams of Z contains 2+2 = 4 grams of X

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