A linear equation has no more than two variables and has a solution that is a single value or ordered pair.
For example: 4s + 6 = 18 is a linear equation with the solution s = 3. x + 5 = 13 is a linear equation with the solution x = 18. 5x + 8y = 13 is a linear equation with a solution (1,1) 2x + 3, 5x^{2}=8, and 4mn = 36 are not linear equations. (Why not?)
