well since the triangle is right angled you know that the given angles sum to 90........(angle sum of a triangle 180, 1 angle = 90) so you can say 3x + 6 + 2x - 1 = 90 or 5x - 5 = 90 now solve for x. the smaller angle will be 2x - 1 so substitute your answer for x and you'll have the measure of the smaller angle. hope that helps
