It means how many differnt combinations are possible so it would just be 6C3 as there are 6 coins, thats what i think though
I have no idea what a loonie and a toonie are - but thats irrelevant. However the above poster is correct - as you are looking for UNIQUE sum. Now not knowing what a loonie or toonie is - I can't say whether or not there is a way of DUPLICATING the sum, without duplicating the UNIQUE combinations. I doubt it though.