Answer:
15m
Explanation:
The third side = (2/3 - 1/5) of the perimeter = 7/15 of the perimeter = 7m
The first side is 1/3 (=5/15) of the perimeter = 5m
The second side is then 3m ( or 1/5=3/15 of the perimeter).
The triangle perimeter is 15 meters (=7 m+5m+3m)