Answer:
x = 50
Explanation:
The base angles of an isosceles triangle are the same
The unmarked angle is also x
The sum of the angles of a triangle is 180
x+x+ 80 = 180
2x+80 =180
Subtract 80 from each side
2x+80-80 = 180-80
2x = 100
Divide by 2
2x/2 = 100/2
x = 50