write a knowledge base add.pl with the following rules: // for two variables sum(X,Y):- S is X+Y, write('sum of '),write(X),write('and '),write(Y),write('is ='),write(S). add:- write_ln('Enter the first number:-'), read(First), write_ln('Enter second number:-'), read(Second), S is First+Second, write('sum of '),write(First),write('and '),write(Second),write('is ='),write(S). now we can close this windows and in the main WINDOW either type ['add.pl']. or consult the add.pl file. now you can call this funcation via two ways :- ?- sum(5,44). it will give output as sum of 5 and 44 is 49 or you can call via add. Enter the first number . :| 45. Enter the second Number . :| 45. sum of 45 and 45 is equal to 90. note i have used sum:- instead of add:- so i ha...