There is a theorem that says that if , , .... are independent random variables with mgf's , , .... then the mgf of is .

Using this theorem it seems to me that the since X, Y and Z are i.i.d. random variables then the mgf of V = X + Y + Z is (and that, in fact, X, Y and Z are binomial random variables with n = 3 and p = 0.3).