Task: Question Answering
Input (English): Problem: for each month of a given year except december , a worker earned the same monthly salary and donated one - tenth of that salary to charity . in december , the worker earned n times his usual monthly salary and donated one - fifth of his earnings to charity . if the worker ' s charitable contributions totaled one - seventh of his earnings for the entire year , what is the value of n ? 
Options: a ) 31 / 4 , b ) 33 / 4 , c ) 29 / 4 , d ) 27 / 4 , e ) 25 / 4
Output (English): b