How do you solve a literal equation?

For instance, the formula for the perimeter P of a square with sides of length s is P = 4s. You might need to solve this equation for s, so you can plug in a perimeter and figure out the side length. This process of solving a formula for a given variable is called "solving literal equations".

He is not correct the tub is 18 inches deep and it takes two minutes to fill the tub with three inches of water therefore it would take 12 minutes to fill up the tub if it went at the same rate