The stellar Khan Academy offers free, well-structured online courses in a variety of subjects that you'll find in US schools, and serves as a reliable source for anyone with a hunger to learn. Where ...

In algebra, letters are used when numbers are not known. Algebraic terms, such as \(2s\) or \(8y\), leave the multiplication signs out. So rather than \(2 \times s\), write \(2s\), and rather than \(8 ...