I just need some help on where to get going with this because i tried but cant seem where to go!!!

Show that the hypergeometirc p.m.f given by P(x=K)= (r choose k)(N-r choose n-k)/(Nchoose n)

will converge to the binomial distirubtion (n choose k)p^k(1-p)^n-k if N=pr and N approcrahes infinity

I was thinking of rearranging N to to obtain r=N/p and then puttin that into teh p.m.f but im not sure whether this the right pathway???