If 30% of 100 is greater than 50% of a number by 10, then the number is? Select: A) 40 B) 30 C) 60 D) 80 E) 50

Rationale: "let the number be x 30 % of 100 - 50 % of x = 10 50 / 100 x = ( 30 / 100 * 100 ) - 10 x / 2 = 20 x = 40 answer is a"
Answer: A