Of 300 surveyed students, 20% of those who read book A also read book B and 50% of those who read book B also read book A. If each student read at least one of the books, what is the difference between the number of students who read only book A and the number of students who read only book B?	Choose the correct choice from the following choices:
A) 120	B) 125	C) 130	D) 135	E) 150

Rationale: "say the number of students who read book a is a and the number of students who read book b is b . given that 20 % of those who read book a also read book b and 50 % of those who read book b also read book a , so the number of students who read both books is 0.2 a = 0.5 b - - > a = 2.5 b . since each student read at least one of the books then { total } = { a } + { b } - { both } - - > 300 = 2.5 b + b - 0.5 b - - > b = 100 , a = 2.5 b = 250 and { both } = 0.5 b = 50 . the number of students who read only book a is { a } - { both } = 250 - 50 = 200 ; the number of students who read only book b is { b } - { both } = 100 - 50 = 50 ; the difference is 200 - 50 = 150 . answer : e ."
Answer: E