Question

1+3+5+7+9+11+13+15+17 take any 5 numbers from this and the sum have to be 30 and you can take any number as many times as you want

Answer 1

It is not possible, as adding odd numbers for odd number of times will result in a odd number.

Answer 2

Adding odd numbers an odd number of times produces an odd number. Hence, it's impossible!

4 numbers could make it, though. Remember:

Odd + Odd = Even

(Notice odd number is being added an even number of times 2)

So, odd numbers being added in pairs results in an even number. As 5 is an odd number, accomplishing such is completely impossible, unless an even number be used.