I'm not entirely sure the format you want the answer in but the table filled out is
1 triangle/ perimeter of 17
2 triangles/ perimeter of 22
3 triangles/ perimeter of 27
The relationship is every time you add a triangle the perimeter goes up 5
So it's something like
perimeter= 17+5(# of triangles)
So if P=perimeter and T= # of additional triangles, the relationship would be
P= 17+5t