Equations that have more than one unknown can have an infinite number of solutions. For example, \(2x + y = 10\) could be solved by: \(x = 1\) and \(y = 8\) \(x = 2\) and \(y = 6\) \(x = 3\) and \(y = ...

Removing brackets is to multiply the term outside the brackets by each term inside - also known as the distributive law. Use FOIL to remove a pair of brackets then simplify by collecting like terms.