Given m // n and p is a transversal. Find the value of x.

Explanation:
The alternate exterior angles shown in the diagram are congruent, due to the fact that m is parallel to n.
Set the angle expressions equal to one another. Solve for x.
4x-25 = x+5
4x-x = 5+25
3x = 30
x = 30/3
x = 10