Question 175754
I don't think you mean how to "solve" since this is not set equal to anything.  I think you meant "simplify".  So I will try that for you.  The first thing I would do is to distribute through the minus signs so that you can drop the parentheses.  So

{{{(15x^2-9x+9)-(13x^2+15x+5)-(16x^2+20x+16)-(-7x^2+10x-10)}}} is equal to
{{{15x^2-9x+9-13x^2-15x-5-16x^2-20x-16+7x^2-10x+10}}}
Now, lets group the like terms.
{{{15x^2-13x^2-16x^2+7x^2-9x-15x-20x-10x+9-5-16+10}}}
So all that's left to do is combine like terms.
{{{-7x^2-54x-2}}}