Let total work done by P,Q and R=100 unit, Work done by P and Q=100×70∕100=70 Remaining work done by R=100−70=30 Work done by Q and R=100×50∕100=50 Remaining work done by P=50 Work done by Q=70−50=20 Efficiency of P=50, Efficiency of Q=20 and Efficiency of R=30 Now, we can say P will finish first, If they work alone.