A coolie deposits Rs 150 per month in his post office Savings Bank account.

Let his monthly income be $\mathrm{Rs} \mathrm{x}$.

Then, $15 \%$ of $x=150$

$\Rightarrow \frac{15}{100} x=150$

$\Rightarrow x=\frac{150 \times 100}{15}$

$=1000$

$\therefore$ His monthly income is Rs 1000 .