Equations that have two or more variables are literal equations. Formulas
are one type of literal equation.
When we solve for one of the variables in a literal equation, we get that
variable by itself on one side of the equal sign. This is done the same
way as solving equations: reverse order of operations.
It sometimes helps to circle or box in the variable in which we want to solve
so we know to leave that term alone until it is the only term on that
side of the equal sign.