The base angle = 64°
Step-by-step explanation:
The angles at the top are equal
The angles at the base are also equal
6x + 20 + 6x+20 + 4x + 4x = 360 (sum pof angles in a quadrilateral)
6x+6x+4x+4x + 20 + 20 = 360
20x + 40 = 360
20x = 360 - 40
20x = 320
x = 320/20
x = 16
The base angle = 4x = 4(16)
The base angle = 64°