Answer:
The length of each side of triangle are 19 ft, 24 ft and 38 ft.
Step-by-step explanation:
Let the length of second side be x.
Now given:
Length of first side is 2 times length of second side.
Length of first side = 2x
Also, Length of third side is 5 ft longer than the second side.
Length of third side = 5+x
Perimeter of triangle = 81 ft.
We need to find the length of each side.
Now perimeter of triangle is sum of all three sides of triangle.
Therefore;
Perimeter of triangle = Length of first side + length of second side + Length of third side.

Length of Second Side = 19 ft.
Length of First side = 
Length of Third side = 
Hence the Length of triangles are 19 ft,38 ft,24 ft.