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 Expression is a mathematical phrase that combines numbers and/or variables using mathematical operations. An expression is a representation of a value; for example, variables and/or numerals that appear alone or in combination with operators are expressions. 1  5 + 6 - (3 + 2)/18.  a + b - c.