SOLUTION: _+_+_+_+_=30..you can use only 1,3,5,7,9,11,13,15..u can also repeat the number .

Sorry, you cannot add 5 odd numbers and get an even number.
It's impossible.

ODD+ODD = EVEN
ODD+ODD+ODD = ODD
ODD+ODD+ODD+ODD = EVEN
ODD+ODD+ODD+ODD+ODD = ODD
ODD+ODD+ODD+ODD+ODD+ODD = EVEN
etc.

If you add an odd number of odd numbers you ALWAYS get an ODD number.

30 is NOT an aodd number, so you might as well give up.  

There can be no solution.

Edwin