So you only have to figure each problem out one time, not over and over.
That's the entire point of algebra. Exactly what numerical values are in question is irrelevant. It is about mathematical principles. Now you can sit down today and figure out how many gallons of gas you bought and what the cost was and how many miles you got from that tank and figure out your miles per dollar by reckoning and scratching out a few numbers.
Or you can express the numbers as variables, figure out the relationship and come up with one formula that works every time you plug in the numbers.
It all depends on how many times you like to solve the same problem.
SD
Guess I just didn't realize how much I've suffered over the years by depriving myself of algebra. (yeah it's sarcasm)