Question

...+...+=30 how to solve using 1,3,5,7,9,11,13,15

Answer 1

We wont get a even number if we add odd numbers an odd number of times. So this has to be solved using factorial- 3! + 11 + 13 = 30. This will be a solution.

Answer 2

There can be many answers but the basic idea is using factorial. Factorial is the product of all the numbers from 1 to that number. For example 4! = 1 x 2 x 3 x 4 = 24.
 
So, 3! + 11 + 13 = 30
Similarly you can find many such answers.

Hope that helps !!