This problem allows a mental solution. If x is the smallest, then the largest is 4x, and then the condition states that x + 2(4x) = 18, or 9x = 18 ====> x = 2. Then the smallest number is 2, the largest number is 4x = 4*2 = 8, and the middle number is the difference 14 - (2+8) = 4.