x = 60 (option B)
Step-by-step explanation:
I will be using an illustration to make it easy to comprehend
l parallel to m:
From the diagram above, the angles opposite each other are called vertical lines.
Vertical lines are equal.
When two lines intersect, the angles opposite each other are equal.
The angles with same collours are corresponding angles. And corresponding angles are equal.
We can see the top (2x + 30)° is equal to the down part with the second brown colour.
And the second brown is equal to the green opposite it (4x-90)°.
2x + 30 = 4x - 90
collect like terms:
2x - 4x = - 90 - 30
-2x = -120
divide both sides by -2:
-2x/-2 = -120/-2
x = 60 (option B)