Task: Question Answering
Input (English): Problem: in the science city , kolkata the rate of the ticket is increased by 50 % to increased the revenue but simultaneously 20 % of the visitor decreased . what is percentage change in the revenue . if it is known that the science city collects one revenue only from the visitors and it has no other financial supports : 
Options: a ) + 20 % , b ) - 25 % , c ) + 305 , d ) - 30 % , e ) can not determined
Output (English): a