Homo and heter

the five homozygous genes will be the same to all gametes. So the difference will be to the rest 5 heterozygous gametes.

Now, in each gamete, each of these five genes can be ether the one type or the other. For convenience, lets say that each of these five genes can be either 0 or 1. If you know binary system, then you must just find how many combinations you can have with 5 digits (the gametes). The answer is 11111 + 1 (it's +1 because we also have the 00000 combination) in binary system, OR
1*2^0+1*2^1+1*2^2+1*2^3+1*2^4 + 1=1+2+4+8+16 + 1=32 in decimal system.

So there are 32 combinations of different gametes.

Well, the way I solved that is quite strange, but I hope I helped...