The difference between a positive proper fraction and its reciprocal is 9/20. The fraction is: Choose the correct choice
A) 2/3  B) 4/5  C) 4/8  D) 9/2  E) 3/7
Explanation:   Let the required fraction be x. Then 1/x-x=9/20   1-x^2/x=9/20   20 - 20x^2 = 9x   20x^2 + 9x - 20 = 0   20x^2 + 25x - 16x - 20 = 0   5x(4x + 5) - 4(4x + 5) = 0   (4x + 5)(5x - 4) = 0   x =4/5   ANSWER 4/5
<result>B</result>
The difference between a positive proper fraction and its reciprocal is 9/20. The fraction is: