In mathematics, a variable expression is an expression that contains operations, numbers, and variables.
For example, if I have 6 coins in my pocket in . addition to the number of coins that are in my jar at home, then then the total number of coins would be represented as X + 6.
X would represent the unknown amount of coins in my jar at home.
This would be a variable expression because it contains an operation "addition", a number "4", and a variable "X."