Simplifying expressions or equations is frequently a key step in solving problems in algebra. To simplify a collection of terms, only those of the same type can be combined. Numbers can be combined with numbers. Terms in \(x\) can be added to or subtracted from terms in \(x\) e.g. \(5x - 2x\) is \(3x\). Terms in \(x^2 \) are different again and must be treated separately. When combining terms, it is essential to take note of the sign in front of each term.