We can represent sums, differences, products, and quotients of rational numbers (and combinations of these) with numerical and algebraic expressions. 

We can write the product of two numbers in different ways.

• By putting a little dot between the factors, like this: $\text-8.5\boldcdot x$.
• By putting the factors next to each other without any symbol between them at all, like this: $\text-8.5x$.

We can write the quotient of two numbers in different ways as well.

• By writing the division symbol between the numbers, like this: ${\text-8.5}\div{x}$.
• By writing a fraction bar between the numbers, like this: $\frac{\text-8.5}{x}$.

When we have an algebraic expression like $\frac{\text-8.5}{x}$ and are given a value for the variable, we can find the value of the expression. For example, if $x$ is 2, then the value of the expression is -4.25, because $\text-8.5 \div 2 = \text-4.25$.