set theory: 3) c and g,

Let x, y, and z be integers. Write a proof by contraposition to show that (a) if x is even, then x + 1 is odd. (b) if x is odd then x + 2 is odd. (c) if x2 is not divisible by 4 then x is odd. (d) if xy is even then either x or y is even. (e) if x + y is even then either x and y are odd or x and y are even. (f) if xy is odd then both x and y are odd. (g) if 8 does not divide x2 1 then x is even. (h) if x does not divide yz, then x does not divide z