Answer:
c 80
Explanation:
The sum of the opposite interior angles is equal to the exterior angle
x +65 = 3x-5
Subtract x from each side
x-x+65 = 3x-x-5
65 = 2x-5
Add 5 to each side
65+5= 2x-5+5
70 = 2x
Divide each side by 2
70/2 =2x/2
35=x
The sum of the angles of a triangle add to 180
x+65+b = 180
35+65+b = 180
100 +b = 180
Subtract 100 from each side
100-100+b =180-b
b = 80