/////If C is lying then the number IS 150 but that would mean that A is also lying but only one person is lying.
No, the question states " You now have all the information needed to figure out the number EXCEPT one of them is lying. it doesn't actually state that only one of them is lying! (a small point, but badly phrased questions permit multiple correct answers)////

That's funny because there ARE multiple correct answers. I never said there weren't. Therefore, by your statement above, I must have worded it exactly correct. If you disagree, then you must agree that your statement above is shit.

Clear on that?