Task: Question Answering
Input (English): Problem: each light bulb at a hotel is either incandescent or fluorescent . at a certain moment , thirty percent of the incandescent bulbs are switched on , and eighty percent of the fluorescent bulbs are switched on . if 70 percent of all the bulbs are switched on at this moment , what percent of the bulbs that are switched on are incandescent ? 
Options: a ) 4.5 % , b ) 8.6 % , c ) 12.3 % , d ) 16.7 % , e ) 20 %
Output (English): b