The average monthly income of P and Q is Rs. 5050. The average monthly income of Q and R is 6250 and the average monthly income of P and R is Rs. 5200. The monthly income of P is____________?

A. Rs. 3500
B. Rs. 4000
C. Rs. 4050
D. Rs. 5000
Explanation:
Let P, Q and R represent their respective monthly incomes. Then, we have:
P + Q = (5050 * 2) = 10100 — (i)
Q + R = (6250 * 2) = 12500 — (ii)
P + R = (5200 * 2) = 10400 — (iii)
Adding (i), (ii) and (iii), we get:
2(P + Q + R) = 33000 = P + Q + R = 16500 — (iv)
Subtracting (ii) from (iv), we get, P = 4000.
P’s monthly income = Rs. 4000