The two triangles are congruent (same size and shape) by the Side-Side-Side congruence postulate (SSS). Notice that the two triangles share a common side--the horizontal line segment.
So angle 2 is the same size as angle 1. m∠1 = 160°.
Think about one of the triangles, say the top one. It is an isosceles triange, so its base angles are congruent. The angle sum in any triangle is 180 degrees, so the two base angles add up to 180 - 160 = 20 degrees. Each base angle must measure 10 degrees.