Answer:
x = 10
Step-by-step explanation:
See image. Due to the logic of vertically opposite angles (when one angle is equal to the other that is "vertically opposite" to it), the two angles that I have marked in the diagram are going to equal.
Therefore, if we were to write it out:
2x + 7x = 90
(vertically opposite angles)
9x = 90
∴ x = 10
