3 + 12 (y-4) = 40
Use distribution
3 + 12y - 48 = 40
combine like terms
-45 + 12y = 40
- what you do to one side of the equation you have to do to the other side
-45 +12y = 40
+45 +45
-----------------------
12y = 85
now you divide to isolate variable
85
------- = 7
12
Y =7
