Amath expression is a collection of one or more terms, which are separated by the signs ( + , - , x , / ).example : 8+b8+b or a−3a−3in algebra, an equation is a mathematical statement with two expressions where, each expression is separated by an equal (=) sign. variables can be present on both the sides of the equality (=) sign and we use letters to denote such variables.example 1: x=4+2x=4+2 , [here, we can observe that the variable is present only on one side of the equation].example 2: 2x+3=x+42x+3=x+4 , [here, we can observe that the variables are present on both side of the equation].