Question

?+?+?=30 solve this fill the boxes using ( 1.3.5.7.9.11.13.15) you can repeat the numbers

Answer 1

as it is not possible to get an odd number by adding odd no.s odd no.of times, we could do it by using factorials,for example:
11+13+3! -=30
[ by this way,you may also find other combinations ]

Answer 2

that is not going to sum of three numbers = 30  from ( 1 , 3, 5,7,9,11 , 13 ,15 all are odd numbers ) while  30 is and even and to chose three numbers only . so, it is not possible .
   if we take  15 + 13 + 1 = 29
                   15 + 11 + 5 = 31
                    5 + 7 +15 = 27
 hence  , it is not possible ..