2023 AMC 10B Problems/Problem 18

Solution (Guess and check + Contrapositive)

Try which makes false. At this point, we can rule out answer A,B,C.

A => B or C. equiv. ~B AND ~C => ~A. Let a = 14, b=15 (statisfying ~B and ~C). => C = 2*210. which is ~A.

is true.

So the answer is E. ~Technodoggo