What two numbers can you multiply to get -16 and add together to get -15

I'm guessing you're trying to factor. Well, because you need to get 15, it's obviously going to be some kind of 16 and 1. But you want a negative product, so one number will be negative. You also want a negative sum, so the bigger number (16) will be negative. Thus, the answer is -16 and 1. Good luck.

8+9-1

-16 and +1

a+b=(-15) b=(-a)-15
a*b=(-16) a*-(a+15)=-16
-a^2-15a+16=0
a=1, b=-16