# Intermediate Algebra/Writing Linear Equations

Linear equations have two variables: and .

## Examples[edit]

If one were doing a walkathon and wanted to raise $5 for every mile walked, an equation for the total money raised, as a function of the number of miles walked, would be . Would donors, however, promise to not only pay $5 per mile but give an additional $30 just for taking part, the equation would be . Note that this example is limited as negative miles don't make sense, but the line defined by the equation is infinite in either direction.