AB + BC = AC since the point C is between A and C on the segment AC. It means that (3x-8) + 4x = 8x - 16. Simplify and solve it for x. 3x - 8 + 4x = 8x - 16 7x - 8 = 8x - 16 16 - 8 = 8x - 7x 8 = x. Thus x= 8, AC = 8x-16 = 8*8 - 16 = 84-16 = 48; AB = 3x-8 = 3*8-8 = 16; BC = 4*x = 4*8 = 32.