The average monthly income of P and Q is Tk. 6,000; that of Q and R is 5,250; and, that P and R are Tk. 5,500. What is P’s monthly income?

Question: The average monthly income of P and Q is Tk. 6,000; that of Q and R is 5,250; and, that P and R are Tk. 5,500. What is P’s monthly income?

Solution:
Average monthly income of P and Q = Tk. 6000
Average monthly income of Q and R = Tk. 5250
Average monthly income of P and R = Tk. 5500

Total income of P + Q = Tk. 2 × 6000 = Tk. 12000 .........(i)
Total income of Q + R = Tk. 2 × 5250 = Tk. 10500 .........(ii)
Total income of P + R = Tk. 2 × 5500 = Tk. 11000 ...........(iii)

On adding equation (i) + (ii) + (iii), we get
2 (P +Q + R) = 12000 + 10500 + 11000
P + Q + R = 33500/2
P + Q + R = Tk 16750 ........(iv)
by equation (iv) - (ii)
P's income = (16750 - 10500) = Tk. 6250.