The S.I on certain sum of money for 15 months at rate of 7.5% per annum exceed the S.I on same sum at 12.5% per annum for 8 months by Rs 3250 find sum?

Let sum =????

$x imes frac{{15}}{{12}} imes 7.5 imes frac{1}{{100}} - x imes 12.5 imes frac{8}{{12}} imes frac{1}{{100}}$

=3250

$frac{3}{{32}}x - frac{x}{{12}} = 3250$

$frac{{9x - 8x}}{{96}} = 3250$

????=96×3250

????=312000