Two numbers are less than a third number by 30% and 37%. How much percent is the second number is less than the first? Choose the correct choice from the following choices:
A) 10 % B) 15 % C) 20 % D) 25 % E) 30 %

Rationale: let the third number be x first number = 70 % of x = 7 x / 10 ; second number = 63 % of x = 63 x / 100 ; difference = 7 x / 10 - 63 x / 100 = 7 x / 100 ; required percentage = 7 x / 100 * 10 / 7 x * 100 = 10 % answer is a
Answer: A