4. Consider the statement: Vx EZ, x is odd 4|(5x − x³). (a) Is this statement true or false? Justify your answer either with a proof or else with a counter-example. (b) Write the contrapositive of the statement. (c) Write the converse of the statement. 5. (a) Give a direct proof of the fact that n² - 5n+ 6 is even for any integer n. (b) Suppose m and n are integers and m² - 5n is even. Prove that n² - 5m is even.