Carlton's advice is a good way to get this problem started. I will start where he left off.
3y -6 = 5 -15y
We want the y's on one side of the equal sign and everything else on the other side. I will put the y's on the left. Add 15 y to both sides. (What you do to one side, you must do to the other.)
3y -6 +15y= 5 -15y+15y
Adding 15y had the effect of moving all the y terms to the left side. Noe add 6 to both sides.
18y -6 +6 =5+6
Now divide both sides by 18.
To check, write the original problem, but put 11/18 in for y. If the equation is true, then the answer is correct.
Since the equation is true, our answer y=11/18 is correct.