Suppose that a and b are integers, a = 3 (mod 13), and b=8 (mod 13). Find the inte- ger c with 0c 12 such that (i) c= 19a (mod 13) (ii) c = 11b (mod 13) (iii) c = 2a+3b (mod 13) (iv) c = a-b (mod 13)