Answer:
Isoceles triangle
40°
Explanation:
You see the two lines on each side of the triangle, that means it's parallel. Isoceles triangles have 2 parallel sides and 2 same angles.
Angles in a triangle add to 180°, so 180-100=80°.
We know both angles are the same size because they are parallel, so 2x = 80°
1 angle must = 40° then