Pg 312 (324) - Q7
Remember that there are 180 degrees in a triangle; so, the triangle on top is going to have 30 and 40 degrees as two of the angles. Therefore, that other angle is 110 degrees. And, intersecting lines from vertical angles and opposite vertical angles are equal; so, the angle on the opposite side of it would also be equal to 110. Since 110+45=155, the value of X is 25 degrees, or answer E.