procedure TForm1.Button1Click(Sender: TObject);
var
x1,x2,y :Integer; begin
x1 := StrToInt(Edit1.(①));
x2 := StrToInt(Edit2.(②));
Case (③).ItemIndex of
0: y := x1 + x2 ;
1: y := x1 - x2;
2: y := x1 * x2;
3: y := x1 Div x2;
End;
Edit3. (④) := IntToStr(⑤);
end;