$$9x + 8x = 136$$
$$17x = 136$$
$$x = 136 : 17$$
$$x = 8$$
$$38x - 25x + 18 = 200$$
$$13x = 200 - 18$$
$$13x = 182$$
$$x = 182 : 13$$
$$x = 14$$
Ответ: a) 8; б) 14.