Question

_+_+_=30
numbers should be->{1,3,5,7,9,11,13,15}
and they may be repeated

Answer 1

it is not possible case only with odd numbers because the sum of odd 3 numbers doesnt result an even number. i.e., we cant get 30 by using those numbers. to get 30 we have to take one number as 3! (3×2×1) = 6
    so  3!+15+9=30

Answer 2

let the numbers be a,b,c and are odd
a + b = odd + odd = even,
even + c = even + odd = odd
therefore its not possible