of 1000 surveyed students , 20 % of those who read book a also read book b and 25 % 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 ?
"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 25 % of those who read book b also read book a , so the number of students who read both books is 0.2 a = 0.25 b - - > a = 1.25 b . since each student read at least one of the books then { total } = { a } + { b } - { both } - - > 1000 = 1.25 b + b - 0.25 b - - > b = 500 , a = 1.25 b = 625 and { both } = 0.25 b = 125 . the number of students who read only book a is { a } - { both } = 625 - 125 = 500 ; the number of students who read only book b is { b } - { both } = 500 - 125 = 375 the difference is 500 - 375 = 125 . answer : b ."
subtract(multiply(multiply(divide(1000, subtract(add(divide(divide(25, const_100), divide(20, const_100)), const_1), divide(25, const_100))), divide(divide(25, const_100), divide(20, const_100))), subtract(const_1, divide(20, const_100))), multiply(divide(1000, subtract(add(divide(divide(25, const_100), divide(20, const_100)), const_1), divide(25, const_100))), subtract(const_1, divide(25, const_100))))