If it exists, find the most general unifying substitution for each of the following pairs of sentences. 1. A(x, Farid) and A( Shikri, Farid) 2. foo(Farid, a, goo(Shikri)) and foo(Z, a, goo(moo(Z)) 3. Divisible (0,x) and Divisible( x, one) (this says that 0 is divisible by all numbers and every number is divisible by 1.).