Answer:
x=12
Step-by-step explanation:
Lines A and B are parallel, with a transversal passing through them.
The properties of two parallel lines and a transversal tells us that angles 5x and 4x+12 must be equal, because they are a pair of alternate exterior angles.
To solve for x, we do 5x=4x+12
Subtract 4x on both sides
x=12
