Good question.
Basically, your money.
Algebra is pretty useful for a number of problems in your job and managing your money.
Your teacher probably gives you "real world problems" that apply principles in algebra to the real world.
That being said, if you are pursuing a career in STEM fields, then you definitely need to learn algebra and a few other higher level math courses.
If you're not pursuing a career in STEM, then you learn algebra for your money, which is pretty important to everyone.
