Let's use X to represent amount of distance we do not know, the amount of distance to the beach.
he drives 5 miles to the beach, plus X miles to the beach for a total of 12 miles.
X + 5= 12
Now, lets figure out what X is. To figure out what X is, you have to get it by itself.
To do this, subtract 5 from both sides.
X + 5 -5= 12 -5
X = 7.
7 miles to the beach.