Answer:
x = 65 degrees
Explanation:
Let's say z=the angle adjacent (next to) to the 145 degrees angle.
80 + x + z = 180 ==> 180 is the total number of degrees in a triangle
z + 145 = 180 ==> In addition, if you add up Angle z and 145
degrees, you get a straight line which totals to 180
degrees
z + 145 - 145 = 180 - 145 ==> solve for z
z = 35 degrees
80 + x + z = 180
80 + x + 35 = 180 ==> plug in 35 for z
80 + 35 + x = 180
115 + x = 180 ==> solve for x
115 - 115 + x = 180 - 115 ==> simplify
x = 65 degrees