Task: Question Answering
Input (English): Problem: if a function f is defined by f ( x ) = - 1 / x for all non zero numbers x. if f ( a. = - 1 / 3 and f ( ab. = 1 / 6 then b = ?
Options: a. 2, b. 1 / 2, c. - 1 / 2, d. - 2, e. - 12
Output (English): d