Answer:
6
Step-by-step explanation:
Since this is a right angle, it will ultimately equal 90 degrees. So right there, you can take away 72 from 90 to see what you have left to work with. This gives you 18. You also have 3y, and the angle it's at is 18 degrees, so you can write this as 18=3y. Next, you have to isolate y, so you divide both sides to get 6=y.
Hope this helped!
