a corporation 5 times its annual bonus to 10 of its employees . what percent of the employees ’ new bonus is the increase ? Choose one: A) 12 % B) 18 % C) 80 % D) 20 % E) 15 %

Rationale: let the annual bonus be x . a corporation triples its annual bonus . so new bonus = 5 x . increase = 5 x - x = 4 x the increase is what percent of the employees ’ new bonus = ( 4 x / 5 x ) * 100 = 80 % hence c .
Answer: C