A student was asked to find 4/5 of a number. But the student divided the number by 4/5, thus the student got 36 more than the correct answer. Find the number. Pick one
A) 60 B) 70 C) 80 D) 90 E) 100

Rationale: "let the number be x . ( 5 / 4 ) * x = ( 4 / 5 ) * x + 36 25 x = 16 x + 720 9 x = 720 x = 80 the answer is c ."
Answer: C