Answer:
x = -12
Explanation:
This is an isosceles triangle (by the markings). That means that angle 2 and the one not marked next to it both have the exact same measure. By the Triangle Angle-sum theorem, all the angles of a triangle have to add up to equal 180. That means that 180 - 36 = angle 2 + the other angle.
180 - 36 = 144 and
144 / 2 = 72. So angle 2 and the other angle both measure 72 degrees. If the expression for angle 2 is x + 84, then 72 = x + 84 and x = -12