Answer:
x=12
Explanation:
The given angles are alternate interior angles, and assuming Lines l and m are parallel, then the given angles are congruent/equal.
We can use this information to set up an equation:
13x-21=5x+75
Add 21 to both sides
13x-21+21=5x+75+21
13x=5x+96
Subtract 5x from both sides
13x-5x=5x-5x+96
8x=96
Divide both sides by 8
(8x)/8=(96)/8
x=12