You have to fill the boxes to make the equation true:
+ + = 30
Using only 1, 3, 5, 7, 9, 11, 13, 15.
You can also repeat the numbers. (eg: 1 + 1 + 1)
Edit1: the boxes of the equation are empty right now
That's my first post here and I didn't realize how fantastics your mind was, that's why my question was so broad. I'll accept the answer I was expecting but it doesn't mean that the other are wrong. Let's the upvoter decide.