Hey there!
When finding this length, we need to remember that there are two congruent side, which are to base angels.
We need to remember that the sum was result in being 180°
So, in this case, we would do

=16.
we then do 180 - 16, and from this, we should get 164°
Your answer
. . .

I hope this is right, :)
~Jurgen