Question

What is the answer to -10r+6+r+5

Answer 1

$Summing\ free\ numbers\ and\ all\ r:\\\\-10r+6+r+5=-9r+11\\\\Answer \ is\ -9r+11.$

Answer 2

-10r + 6 + r + 5  is not a question, so there's nothing to answer, and it's not an equation, so there's nothing to solve.

Maybe your assignment says something like "simplify it", or "combine like terms".
That just means clean it up and make it prettier to look at and easier to work with.
If that's the question, then here's the answer:

-10r + 6 + r + 5

Do you see the  -10r  and the  +r  in there ? 
                                    You can combine them into '  -9r '.

Do you see the  +6  and the  +5  in there ? 
                                     When you add those together, they make  +11 .

So now, the original expression became:        -9r + 11 .

Nothing has changed. The shorter one still has exactly the same value as the original one. But it's a lot simpler, neater, easier to read, and easier to work with.