please answer 3abc. thanks

3. a) Prove that the following is true for all positive integers n: n is even if and only if 5n2 4 is even. b) Prove using the rules of inference that the premises prar imply qp. c) Prove using the rules of inference that the premise vx((W(x) B(x)) (W(x) B(x))) implies the conclusion Vx (W(x) B(x)). 3. a) Prove that the following is true for all positive integers n: n is even if and only if 5n2 4 is even. b) Prove using the rules of inference that the premises prar imply qp. c) Prove using the rules of inference that the premise vx((W(x) B(x)) (W(x) B(x))) implies the conclusion Vx (W(x) B(x))