Given
4n - 18 = 22
Add 18 to both sides:
(4n - 18) + 18 = 22 +18
4n = 40
Divide 4n to both sides
=

n=10
Now if you have to you can substitute n into the original equation and see if they are equal to one another.
4n - 18 = 22
4(10) - 18 = 22
40 - 18 = 22
22 = 22
With this being done n = 10