Work and wages for painting a house

In 6 days:

• Anil completes $\frac{6}{12} = \frac{1}{2}$ of the work.
• Barun completes $\frac{6}{16} = \frac{3}{8}$ of the work.

Together, Anil and Barun complete: $\frac{1}{2} + \frac{3}{8} = \frac{7}{8}\text{ of the work}$

Hence, Chandu completes the remaining work: $1 - \frac{7}{8} = \frac{1}{8}\text{ of the work}$

Chandu's payment = $\frac{1}{8} \times 24000 = ₹ 3000$.