A triangle perimeter = side1+side2+side3=49ft
Where side1=side2 because 2 of the sides equal
And side3=side1+4ft because side3 is 4ft more than the length of an equal side
Plug them in
49ft=side1+side1+(side1+4ft)
simplify
Subtract 4 from both sides
45ft = side1+side1+side1
45ft = 3*side1
Divide both sides by 3
15ft = side1
Side1 =side2=15ft
Side3=side1+4ft= 15+4=19ft