proc sort data = ia.expenses out = expenses;
   by FlightID Date;
run;

proc sort data = ia.revenue out = revenue;
   by FlightID Date;
run;

data exprev;
   merge expenses(in = e) revenue(in = r);
   by FlightID Date;
   if e and r;
   Profit = sum(Rev1st, RevBusiness, 
                RevEcon, - Expenses);
run;

proc sort data = exprev;
	by Dest;
run;

proc sort data = ia.airports;
	by Code;
run;

data ia.alldata;
   merge exprev(in = exp) ia.airports
         (rename = (Code = Dest) 
          keep = City Name Code);
   by Dest; 
   if exp;
run;

proc print data = ia.allData(obs = 5) noobs;
   title 'Result of Merging Three Data Sets';
   format Date date9.;
run;