Well, it's a simple problem. You could just find the possible combinations of picking differing sets of weight. Combinations of 1 weight picked from 5, combinations of 2 weights picked from 5, combinations of 3 weights picked from 5... Etc. You use the following formula for n being the total number of weights and r being the number of weights you're choosing:

For r=0:

For r=1:

For r=2:

For r=3:

For r=4:

For r=5:

Now you add them all together:

That tells you that there are 32 possible combinations