How do you solve 5/4 + y = -9?

5 + 4y = - 36
4y = - 41
y = - 41/4
y = - 10¼

5/4 + y = -9
y = -9 - 5/4
y = -9 - (1 1/4)
y = -10 1/4 (-10.25)

What you have to do is realize what you are trying to do here. You are trying to simplify y. So, you have to make y by itself. The only way you can do that is by removing numbers away from y's side. If you subtract 5/4 away from each side of the problem, then y is by itself so lets do that.
5/4 - 5/4 = 0 -9 - 5/4 = -9 5/4
Your problem now looks like this y = -9 5/4
-9 5/4 is not simplified all the way because of the improper fraction. -9 5/4 = -10 1/4.
You now have y= -10 1/4

y= -10 1/4 is the answer.

p.s. the guy above me is wrong because he put 5/4 + y = 9 instead of 5/4 + y = -9.

5/4 + y = -9
y = - 9 -5/4
= -36 -5/4...turning them into quarters so that they can be added.
= -41/4
= -10 1/4/

y= - 9 + 5/4

y= -36/4 + 5/4

you do the rest

One way would be to multiply both sides of the equation by the lowest common denominator, in your case 4, like so:

5/4 + y = -9 | * 4 (multiply both sides by 4)

4*(5/4 +y) = -9*4

5+4y=-36
4y=-36 - 5
4y=-41 | / 4 (divide both sides by 4)
y=-41/4