First question:
Reduce the ratio
150 ml
------------
0.3 l
Do this by use of the appropriate conversion factor:
150 ml 1 liter 150 liter
------------ * ------------ = ------------- = 0.5 liter.
0.3 l 1000 ml 300
Darren drinks more milk: 0.5 liter versus Randy's 0.3 liter.