function Check(num : integer) : boolean;var sum : integer;begin while num > 0 do begin sum := sum + num mod 10; num := num div 10; end; Result := (sum >= 20) and (sum <= 30);end;var i, len : integer; sum : real;begin sum := 0; len := 0; for i := 10000 to 99999 do begin if Check (i) then begin len := len + 1; sum := sum + i; end; end; writeln('Среднее арифметическое: ', sum / len);end.