we start with:
-10 = xy + z
When you want to solve for a certain variable, you generally follow pemdas in reverse, so subtract z from both sides first:
-10 - z = xy
And finally, divide both sides by y:
(-10 - z)/y = x
and there we go! sorry for the badly typed equations, I'm on my phone so there's only so much a can do :( hope I helped, and let me know if you have any questions!
