The lines m, l, and n intersect at point Q. What are the measures of the six angles formed by these lines?
(1) The measure of z is one half the square of the measure of x.
Keep in mind that we have lots of vertical angles here...
z = 1/2 x^2 which doesn't tell us a whole lot because we don't know what z or x are. Insufficient.
(2) v + w = 130
if v + w = 130 then x + y = 130 as well because they are opposite angles. z + t are vertical angles and they equal the remainder of angles. z + t = 360 - (x + y) - (v + w) --> z + t = 360 - 130 - 130. z + t = 100 z = t because they are vertical angles. so z, t = 50 But we don't know the rest of the measures. Insufficient.
1 +2) If z = 1/2 x^2 then 50 = 1/2 x^2 --> 100 = x^2 --> x = 10. The opposite angle to x, w = 10 as well.
x + y = 130 --> 10 + y = 130 y = 120. y and it's opposite angle v = 120. Sufficient.
C