The sum of number of boys and girls in a school is 900. If the number of boys is x, then the number of girls becomes x% of the total number of students. The number of boys is?	Choose the most appropriate option.
A) 50 B) 40 C) 60 D) 90 E) 70

Rationale: we have x + x % of 900 = 900 x + x / 100 * 900 = 900 10 * x = 900 x = 90 answer is d
Answer: D