(y+10)(y-4)
Step-by-step explanation:
In order to solve you must set the equation to 0. Meaning you subtract 49 from 9 to get the original equation to now be y^2+6y-40.
You then set that equation (y^2+6y-40) to zero in order to factor it out.
To do this, you have to find two numbers that multiply to make -40 but add to make 6, which is where you get 10 and -4.
Hope this helped! :)