Determine whether these biconditionals are true or false

Determine whether these biconditionals are true or false.

a) 2 + 2 = 4 if and only if 1 + 1 = 2.
b) 1 + 1 = 2 if and only if 2 + 3 = 4.
c) 1 + 1 = 3 if and only if monkeys can fly.
d) 0 > 1 if and only if 2 > 1.