Explanation:
Since 4x + 24 and 7x + 3 are vertical angles, that means they are congruent so we can write:
4x + 24 = 7x + 3
-3x = -21
x = 7°
Since 4x + 24 and z form a linear pair, they are supplementary (meaning they have a sum of 180°) so we can write:
4x + 24 + z = 180
4 * 7 + 24 + z = 180 (Substitute x = 7)
28 + 24 + z = 180
52 + z = 180
z = 128°