Answer is

11.5 + 11.5 + 7

23 + 7 = 30

Choose 3 numbers= 13, 11 and 3!

We know 3!( 3 factorial) = 3×2×1= 6

13 +11 + 3! = 13 +11 +6 = 30

Another answer:

You can also add 15+9+3! = 15+9+6 = 30

No 9...Water melon is upside down. So, 6+11+13 = 30

9 numbered water melon is upside down... So, 6. Now 6+11+13 = 30

Hello Tarun Teja.

It is not possible because according to rule of mathematics sum of two odd numbers is always even, take any example. 3+5=8.  7+13=20 etc and then sum of one odd and one even number is always odd number hence in no combination odd and even can turn up to be even which is 30.

Hope you get it