Hello from MrBillDoesMath!
Answer:
x = 110
Discussion:
The triangle is isosceles so if we call the base angles "y", then
40 + y + y = 180 => as a triangle has 180 degrees
40 + 2y = 180 => subtract 40 from both sides
2y = 180 - 40 = 140 => divide both sides by 2
y = 140/2 = 70
Focus on the left base angle:
x + 70 = 180 => a line has 180 degrees.
x = 180 - 70 => subtract 70 from both sides
x = 110
Thank you,
MrB
