What rate present does a man get for his money when in discounting a bill due 10 months hence he deducts 10% of the amount of the bill ?

Let amount of the bill = Rs. 100. Money deducted = Rs. 10
Money received by the holder of the bill = Rs. (110 - 10) = Rs. 90
∴ S.I. on Rs. 90 for 10 months = Rs. 10
$$\eqalign{ & \therefore {\text{Rate}} = \left( {\frac{{100 \times 10}}{{90 \times \frac{{10}}{{12}}}}} \right)\% \cr & \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, = 13\frac{1}{3}\,\% \cr} $$