Hi!
The line of symmetry is a line that has equal parts of the shape on both sides of it.
Look at the shape. Is there a place where you can put a line that divides it in half? Or will one part of it still be unequal?
I included an image that shows the line of symmetry. Note how the halves of the triangle on both sides of the line are equal.
The line of symmetry is x = 3
Hope this helps! :)
-Peredhel