Answer:
x = 70
Explanation:
The Left base angle is also = x. that's because both angles are opposite = lines
x + x + 40 = 180 All triangles have 180 degrees.
2x + 40 = 180 Combine left angles. Subtract 40 from left and right sides.
2x+40 - 40 = 180 - 40 Combine
2x = 140 Divide by 2
2x/2 = 140/2
x = 70