P,Q and R together earn Rs.1620 in 9 days. P and R can earn Rs.600 in 5 days. Q and R in 7 days can earn Rs.910. How much amount does R can earn per day ?

Amount Earned by P,Q and R in 1 day = 1620/9 = 180 —(1)Amount Earned by P and R in 1 day = 600/5 = 120 —(2)Amount Earned by Q and R in 1 day = 910/7 = 130 —(3)(2)+(3)-(1) => Amount Earned by P , Q and 2R in 1 day– Amount Earned by P,Q and R in 1 day = 120+130-180 = 70=>Amount Earned by R in 1 day = 70