The angle formed by two tangles results in half of the difference of the two arcs.
That is to say
70 = .5(Major arc - minor arc)
Think of the major arc as the larger and the minor the smaller.
So therefore the difference in the two arcs = 140 (multiplying both sides of the above equation by 2.
140 = major arc - minor arc.
Another necessary idea is that the arc of a whole circle = 360 degrees, that is to say the major arc + minor arc = 360, giving us a second equation to solve.
Assuming x is the minor arc.
140 = major arc - x
360 = major arc + x
Use linear combination and add these equations to get
500 = 2*major arc
major arc = 250
minor arc or x = 110.
The answer is 110 degrees.