Had they been sold at standard mix they would be as follows:
X: 800/2,400 x 2,250 = 750 Y: 1,000/2,400 x 2,250 = 937.5 Z: 600/2,400 x 2,250 = 562.5
It may help you to watch my free lectures on this. The lectures are a complete free course for Paper PM and cover everything needed to be able to pass the exam well.