In a college the ratio of the numbers of boys to the girls is 5:7. If there are 140 girls, the total number of students in the college is?	Choose the correct choice from the following.
A) 200  B) 240  C) 160  D) 250  E) 310

Rationale: "let the number of boys and girls be 5 x and 7 x then , 7 x = 140 x = 20 total number of students = 12 x = 12 * 20 = 240 answer is b"
Answer: B