Hmm... It would have been better if you had written out the intended value of your 'c'... Assuming it means 'cup', there is still the problem of whether you mean a metric cup (250ml), or a U.S. Standard cup (236.588238ml)... However, since you are asking which is smaller, and a half cup is 118.294119ml (125ml for metric), no matter which you mean, the 45ml is definitely smaller... As it is less even than 0.25 cup...
