Let the second side = x
The first side is 2x ( 2 times the second side)
The third side is x + 6 ( 6 feet longer than the second side)
Now you have: x + 2x + x + 6 = 34
Simplify to get:
4x + 6 = 34
Subtract 6 from both sides
4x = 28
Divide both sides by 4:
X = 7
1st side = 2x = 2*7 = 14 feet
2nd side = x = 7 feet
3rd side = x + 6 = 7 + 6 = 13 feet