pls help

By  the triangle inequality  

2n +15  + 3n >  n + 30

5n + 15 >  n + 30

4n < 15

n < 15/4

n < 3.75

And

n + 30 +  2n + 15  >  3n

3n + 45  >  3n 

True for all positive  n

And

3n + n + 30  >  2n + 15

3n + 30  > 2n + 15

n >  -15

Assuming  that  we  want  positive  integer  answers.....

n =  ( 1, 2 , 3)

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