What is the solution to finding the angle in this geometry homework problem?

[golb0016]

Homework Statement

See the attachment

The Attempt at a Solution

Is the answer simply 70-40=30?

 

[Mark44]

You're trying to find angle 1, right? It looks to me like you are given that it is 40 degrees.

 

[GunnaSix]

I'm pretty sure 40 degrees refers to that arc of the circle. In this case, you need two formulas:

1) Angle inside circle equals one-half of the sum of the intercepted arcs.
2) Angle outside circle equals one-half of the difference of the intercepted arcs.

 

[golb0016]

70 = .5 (40+x)
x = 100

Angle 1 = .5(100+40)
Angle 1 = 70

However this answer is not an option. Where is my mistake?

 

[GunnaSix]

Angle 1 = .5(100+40)

Your mistake is in this line. The angle outside the circle is equal to half the difference of the intercepted arcs.