An expression that has both numbers and letters in it is called an algebraic expression. In the expression 3x – 2y there are two terms, 3x is an algebraic term, where 3 is the coefficient and x is a variable; – 2y is the other algebraic term, where – 2 is the coefficient and y is a variable.
When adding and subtracting terms within an algebraic expression, the terms that have the same variable go together.
x + x + x = 3x
a + a + b + b + b – b = 2a + 2b
When multiplying an algebraic term by a number, multiply the coefficient of the algebraic term by the number.
a × 5 = 5a
4 × 3b = 12b