Question

?+?+?=30
(You can use numbers 1,3,5,7,9,11,13,15 only)
-the numbers can be reapeated

Answer 1

Hiiiii

the sum of three odd numbers can never be equal to an even number.

But there is no mention if you can use sign within the braces or not. So..

(11–1)+(13–3)+(15–5)

=10+10+10

=30

Hence proved

@skb