reserve X for set;
reserve a,b,c,k,m,n for Nat;
reserve i,j for Integer;
reserve r for Real;
reserve p,p1,p2 for Prime;

theorem Th30:
  m * n = 50 implies m = 1 & n = 50
                  or m = 2 & n = 25
                  or m = 5 & n = 10
                  or m = 10 & n = 5
                  or m = 25 & n = 2
                  or m = 50 & n = 1
  proof
    assume
A1: m*n = 50;
    m divides m*n;
    then m = 1 or m = 2 or m = 5 or m = 10 or m = 25 or m = 50 by A1,Th16;
    hence thesis by A1;
  end;
