Sharon used more milk because 3 cups equal 1.5 (one and a half) pints.
Detailed answer:
1 cup equals 0.5 pints or half of a pint. So if you take 0.5 and multiply it by 3 you get 1.5 and that is the amount of pints that Sharon uses but Sue uses 1 pint or 2 cups. so 1.5 pints is grater than 1 pint by 0.5
(sorry if this was not so clear i am not that good at explaining things, also i hope this helps and you get a good score on whatever you are doing.)
