Task: Question Answering
Input (English): Problem: a couple who own an appliance store discover that if they advertise a sales discount of 10 % on every item in the store , at the end of one month the number of total items sold increases 30 % . their gross income from sales for one month increases by what percent ? 
Options: a ) 9 % , b ) 11 % , c ) 13 % , d ) 15 % , e ) 17 %
Output (English): e