Definition of dray. : a vehicle used to haul goods; especially : a strong cart or wagon without sides.
The main difference between an equation and a function is the fact that an equation usually deals with a single input, whereas, a function can have numerous inputs. In mathematics, an equation is used to denote the equality between two expressions.
An equation is simply a number sentence with a variable in the place of an unknown value. A variable is a letter that is substituted in place of the unknown value. It can be any letter you want, although x is most commonly used. To unlock this lesson you must be a Study.com Member.