Question

What is x? i do not know how to do this

Answer 1

x=41 yeah thats it ......

Answer 2

since you know that a triangle's angles=180, you have 2 of the angles. You also know that the sum of 2 angles is equal to 180 minus the exterior angle. So,

2x+x=123
3x=123
x=123/3
x=41, 2(41)=82 for the other angle.