Answer:
12 ft, 13 ft , 17 ft
Explanation:
let x be the length of the second side , then
one side is x + 1
third side is x + 5
the perimeter P is the sum of the 3 sides, then
P = x + x + 1 + x + 5 ← collect like terms
P = 3x + 6
given P = 42 , then equating gives
3x + 6 = 42 ( subtract 6 from both sides )
3x = 36 ( divide both sides by 3 )
x = 12
x + 1 = 12 + 1 = 13
x + 5 = 12 + 5 = 17
the 3 sides are 12 ft, 13 ft , 17 ft