Answer:
5 ft
Step-by-step explanation:
If all sides are of the same length, we can multiply the value of one side by 3, because a triangle has three sides (and the perimeter is all sides added together), to find the perimeter.
 × 3
 × 3
 can be rewritten as
 can be rewritten as  , so:
, so:
 ×
 × 

The numerator & denominator share a common factor of 3, so:
5 ft is the final answer/perimeter.
hope this helps!