The two triangles with the given perimeter is attached .
Perimeter is the sum of all sides.
For the first triangle , sies are 2a,2a and b.
So the perimeter is
[tex]Perimeter = 2a+2a+b \\ Perimeter = 4a+b[/tex]
For the second triangle, sides are a,a, and 2a+b. Therefore perimeter is
[tex]Perimeter = a+ a + 2a+b \\ Perimeter = 4a+b[/tex]
So for both triangles, perimeter is
[tex]4a+b[/tex]