P and Q can finish a work in 10 days and 5 days, respectively. Q worked for 2 days and left the job. In how many days can P alone finish the remaining work?

6 days

P = 10 days, Q = 5 days,

⇒ Q worked for 2 days alone = 2 x 2 = 4 units,    ..(Efficiency × Days = Total work)

⇒ Remaining work = 10 - 4 = 6 units,

⇒ Time required by P to complete the work alone = \(\frac{6}{1}\) = 6 days,  ..(\(\frac{Work}{Efficiency}\) = Time)