People usually think that some or most subjects in school are useless, and to a certain extent, they are right. However, even though I can find many examples of how you use that knowledge in real life, the point of going to school is not to apply 'classroom content' in your daily life. Think how many times you've apply specific classroom content in your daily life? My guess is, not very often. The real point of going to school is to exercise your brain. Algebra is based on logic; when you learn it and practice it, you are really learning how to solve logical problems and to think logically. Other subjects will develop or continue development of same or different parts of your brain. How many times have you applied a specific formula with the exact same variables you learned at school in "classroom algebra' in real life? Now, how many times have you made a recipe smaller because you are cooking for less persons than it's designed for? Or how many times while grocery shopping you noticed your favorite product comes in two different sizes, and you've actually figured out the better deal or which is cheaper in a per-ounce basis? For the recipe and which is cheaper situation, you use algebra to solve it, although you don't realize it.
Think of a professional athlete, a basketball player for example, and all the time he spends in the weight room doing bench presses, leg presses, back squats, curls, etc. Of course he practices his drills like dribbling and shooting that help him in the game, but when is he ever going to need to lift heavy objects during a game? probably never (unless a basketball and all of its 22 ounces qualifies as a heavy object and it justifies all the heavy lifting in the weight room). Then why does he still do it? he conditions and builds up his muscles so that he can perform the skills he needs to do during the game, better. Same goes for the material you learn and practice in school, and your brain.