a can be one of these: 205, 215, 225, 235, 245
b can be one of these: 0.35, 0.40, 0.45, 0.50
c can be 17 or 18
what are all the possible results with the above combinations?
Just looking at the total amount of combinations, including repeats, take the number of elements in each category and multiply them together. So if there are five elements in a, 4 in b and 2 in c the total possibilities are 5*4*2=40. Now the only problem is if we have repeats we need to remove them from the list. If (a*b*2)=D could be made from more than one combination of elements we would subtract from 40, but from a quick glance I don't see any repeats.