Question

what is the value of s?

Answer 1

I'm a little confused on how to do this question, here are the choices
a.35
b.55
c.70
d.90
can some one explain how I would solve this problem?

Answer 2

angle s is an inscribed angle (in a circle) so it is ½ the "intercepted arc"

notice that the 110º + the intercepted arc add up to ½ of the circle (i.e. 180 deg)
so you can find the intercepted arc
and ½ of that is angle s

Answer 3

Do you know of any tricks or could you explain how this is done?

Answer 4

First see
http://www.khanacademy.org/math/geometry/cc-geometry-circles/central-inscribed-circumscribed/v/inscribed-and-central-angles

There is no "trick"... you just need to learn the ideas.
after watching the video, re-read what I posted up above. It should make sense.