52+4y=12
We move all terms to the left:
52+4y-(12)=0
We add all the numbers together, and all the variables
4y+40=0
We move all terms containing y to the left, all other terms to the right
4y=-40
y=-40/4
y=-10
_______________________________________________________
3.1-3y=18
We move all terms to the left:
3.1-3y-(18)=0
We add all the numbers together, and all the variables
-3y-14.9=0
We move all terms containing y to the left, all other terms to the right
-3y=14.9
y=14.9/-3
y=-4+2.9/3