Saying, for example, 25 years is Arithmetic, a known value. Saying d = xy is Algebra, an unknown value. By the way, saying for example, it's 5:24 or 5h and 24m is Arithmetic. Saying t = xh:xm is Algebra. t is time.
No that is not algebra. Against all logic in your 'equation' the units are replaced with a y. So again all you have d = x. I don't know what that is, but it sure isn't algebra!
Algebra is the branch of Mathematics that generalizes accounts, for example, with letters. In another sense, A = xy (age is equal to so many years). A = xy represents all ages in years. M = xm (the movie lasts so many minutes). M = xm represents the duration of all movies in minutes. Perhaps they are not pure equations, but they are generalizations.