As angles opposite congruent sides in a triangle are congruent, and also since the interior angles of a triangle add to 180 degrees, if we let angle EFG have a measure of x, then angle GEF also measures x, and thus:
82+x+x=180
2x=98
x=49
Thus, angle EFG is 49 degrees.
So, by the exterior angle theorem, angle DEG measures 82+49=131 degrees
