A can do a work in 10 days and B can do the same work in 15 days. If they work on it together for 4 days, then the fraction of the work that is left is:

$\frac{2}{3}$ $\frac{3}{5}$ $\frac{3}{4}$ $\frac{1}{3}$

$\frac{1}{3}$

A = 10 days, B = 15 days, ⇒ A+ B worked for 4 days = (3 + 2) x 4 = 5 x 4 = 20 units, ⇒ Remaining work = 30 - 20 = 10 units, ⇒ Fraction of work left = \(\frac{10}{30}\) = \(\frac{1}{3}\)