Use Wilson's Theorem to find the least nonnegative residue modulo m of each integer n below

a. 64!=n and m=67

b. 31!/22!=n and m=11

Also,

Prove that if p is an odd prime number, then 2(p-3)! congruent to -1modp

I missed class due to a wedding and our book only states wilson's theorem...so im really confused..thanks for any help1