Let 'x' represent the salary before the raise. 

You need to convert the percentage to decimals first.

After the first raise of 15% the new salary will be: 1.15x

After the second raise of 10% of the previous salary: 1.10*1.15x = 1.265x

Now, lets compare the final salary to the start salary to find the overall raise:

1.265x - x = 0.265x

Lets convert the decimal back to percentage:

0.265 is 26.5%

So, the overall raise will be 26.5%.