A mathematical expression, also called expression, is a mathematical sentence that includes at least one operation, numbers, and/or variables without an equal sign.
If one TV costs 400 dollars, how can the cost of buying 3 TVs at the same price be expressed?
3 × 400 is the mathematical expression for the cost of 3 TVs.
Suppose n represents the number of TVs you can buy at the same price of 400 dollars. How can the cost of buying n TVs be expressed?
n × 400 is the expression for the cost of buying n TVs.
An expression for 3 plus a number is 3 + x
An expression for the product of 6 and a number could be 6n, 6x, 6y, etc...
An expression for buying two books costing eight dollars each with a discount of three dollars is
2 × 8 - 3