Question 66629
Having one, two, or three variables are used in the same way. The variables are used to make the equation shorter, substatute for an unknown number, and in all three senerios the similarities you have an unknown number, which you would need to use algebraic formulas by either multiplying, dividing, adding, or subtracting to get the unknown number. They are different in the ways in which they are treated to get the unknown number. 
What if you had three variables:
Therefore, the general rule is:
To find one variable you need one equation
To find two variables you need two equations
To find three variables you need three equations
To find n variables you need n equations