A alone can do a piece of work in 30 days. B alone can do the same work in 60 days.If they work together for five days, what fraction of the work will be left?

$\frac{3}{4}$

A = 30 days, B = 60 days,

⇒ A + B worked for 5 days = (2 + 1) x 5 = 3 x 5 = 15 units,   ..(Efficiency × Days = Total work)

⇒ Remaining work = 60 - 15 = 45 units,

⇒ 45 is a part of total work = \(\frac{45}{60}\) = \(\frac{3}{4}\)