If 5y-4=36, then add 4 to each side, creating the new equation 5y=40. If 5y=40, then divide each side by 5, finding your answer, which is y=8.
For the future, just remember that whatever you need to do to isolate the variable, you need to add like terms, if you can, and do the opposite of what is being done to the variable on both sides (like when you divided by 5 on both sides because the y was being multiplied by 5, or when you added 4 to both sides because 4 was being subtracted from 5y).
I hope that I didn't confuse you. Have a good day.
