_+_+_=30

you can use any of these numbers
(1,3,5,7,9,11,13,15) the rules are , you can't use 0,then you can't leave gaps in these blank, then you should use these numbers only.

(3*5-11)+(3*13-15)+(1*11-9)= 30
(15-11) + (39-15) + (11-9 )   = 30
 4+24+2= 30
       30  = 30

So, in this only the numbers given above is used , no gaps are left and I didn't even use 0. 
So, i guess my answer is right.