Monthly income of (A + B) = 2 x 7760 = 15,520 .... (1) Monthly income of (B + C) = 2 x 10990 = 21,980 .... (2) Monthly income of (C + A) = 2 x 9070 = 18,140 .... (3) Adding the above equations, we get : 2(A + B + C) = 15,520 + 21,980 + 18,140 = 55,640 ∴ A + B + C = 27, 820 .... (4) Subtracting equation (4) - (3), we get (A + B + C) - (C + A) = 27, 820 - 18, 140 = 9680 So, Monthly income of B = 9680 Now, Annual salary of B = 12 x 9680 = Rs 1,16,160