Algebra uses letters to represent unknown values. Unknown values are commonly represented by the letters x and y. There are several principles you need to know to be able to use algebraic notation.

Algebra is a branch of mathematics dealing with symbols and the rules for manipulating those symbols. In elementary algebra, those symbols (today written as Latin and Greek letters) represent ...

DR. LODGE'S remarks on p. 513 (April 2), ought not, I think, to pass without protest. He very reasonably objects to being asked to use a formula which is adapted to one particular set of units, and is ...