In any triangle, each side is shorter than the sum of two other sides. It gives three independent inequality 45 < 4x + (2x-4), (1) 4x < 45 + (2x-4), (2) 2x-4 < 45 + 4x. (3) From (1), 6x > 45 + 4 = 49 ---> x >. From (2), 2x < 45 - 4 = 41 ---> x < . From (3), 2x > -4 - 45 = -49 ---> x > . Answer. < x < .