An equation of the form ax+by+c=0 is called a linear equation in which a,b and c are constants (real numbers and x and y are variables each with degree 1(one). A set of two or more equations, each containing two or more variables whose values can simultaneously satisfy both or all the equations in the set, the number of variables being equal to or less than the number of equations in the set. Up to now, we have solved equations with only one unknown variable. When solving for two unknown variables, two equations are required, and these equations are known as simultaneous equations. Simultaneous equations can be used when considering the relationship between the price of a commodity and the quantities of the commodity people want to buy at a specific price. An equation can be written that describes the relationship between quantity, price and other variables, such as income. Solutions are the values of the unknown variables which satisfy both equations simultaneously. In general, if there are n unknown variables, then n independent equations are required to obtain a value for each of the n variables.