In this task, you need to answer the given multiple-choice question on the gain. Gain is the value by which to multiply the input. Classify your answers into 'a', 'b', 'c', 'd', and 'e'.

Problem: a merchant sells an item at a 20 % discount , but still makes a gross profit of 20 percent of the cost . what percent p of the cost would the gross profit on the item have been if it had been sold without the discount ? 
Options: a ) 20 % , b ) 40 % , c ) 50 % , d ) 60 % , e ) 75 %
c

Problem: a grocer has 400 pounds of coffee in stock , 25 percent of which is decaffeinated . if the grocer buys another 100 pounds of coffee of which 60 percent is decaffeinated , what percent , by weight , of the grocer ’ s stock of coffee is decaffeinated ? 
Options: a ) 28 % , b ) 30 % , c ) 32 % , d ) 34 % , e ) 40 %
c

Problem: john and david can finish a job together in 4 hours . if john can do the job by himself in 5 hours , what percent of the job does david do ? 
Options: a ) 20 % , b ) 25 % , c ) 24 % , d ) 23 % , e ) 22 %

a