The sum of numbers at the extremities of the three line segments in each figure is same. In fig. (A), 39 + 33 = 29 + 43 = 27 + 45 = 72 In fig. (B), 42 + 31 = 29 + 44 = 30 + 43 = 73 Let the missing number in fig. (C) be x. Then, x + 10 = 59 + 20 = 40 + 39 = 79 or x = 69.