need number 3

(d) The set{w.na w mod 3 > n(w) mod 3} (2) (10 points each) Find a context-free grammar for the following languages: (a) L= {w e{a,b}" : na(w) + n)(w)} on 2 = {a,b}. (b) L={a".b" : nm-1} on = {a,b}. (c) L={a".w.wk.b":w *,n> 1} on L = {a, b}. (Note that w is the reversed string of w.) (3) (10 points each) Find a context-free grammar for the languages L, L' and I where L={a".b":n> 1} on = {a,b}