4. (3%) Let p= 101 be a prime and a = 2 be a primitive root modulo p. Please determine the value of (a7)9 mod p. (A) 88 (B) 89 (C) 90 (D) 91

11. (3%) Let x= a+ bk be the solution of the system of congrucnces x = 7 (mod 9), x≡ 4 (mod 12),and x≡16 (mod 21), where a and b are the smallest positive integer, k e Z. Which is the correct value of (2a+b) mod 11? (A)9 (B) 7 (C) 4 (D) 6