Prove each statement by contrapositive a. For every pair of real numbers r and y, if r + y is irrational, then is irrational or y is irrational
b. For every pair of integers z and y. if ry is even, then r is even or y is even.
c. For every pair of integers z and y, if z - y is odd, then r is odd or y is odd.
d. For every pair of real numbers r and y, if r + y 20,then >10 ory 10
e. For every pair of positive real numbers x and y, if xy >400, then > 20 ory>20 Feedback?