Start with the inner most brackets and work your way out.
$$10+4-(3-(1+2-(4-9)))\\ =14-(3-(3-(-5)))\\ =14-(3-(3--5))\\ =14-(3-(8))\\ =14-(3-8)\\ =14--5\\ =14+5\\ =19$$
why wont you just check it in the calculater? its 19