Average income of 50 families is Rs. 3,000. Of these average income of 12 families is Rs. 1,800. Find out the average income of the remaining families.

The average income of A, B and C is Rs. 12,000 per month and the average income of B, C and D is Rs. 15,000 per month. If the average salary of D be twice that of A, then the average salary of B and C is (in Rs.) :

The average monthly income of P and Q is Rs 5050. The average monthly income of Q and R is Rs 6250 and the average monthly income of PP and R is Rs 5200. The monthly income of P is (a) Rs 3500 (b) Rs 4000 (c) Rs 4050 (d) Rs 5000