Concept

To evaluate an algebraic expression means to substitute the value(s) given for the corresponding variables and then use the proper order of operations to solve.

Rule

When a number (x) is given, insert the number into the expression for the corresponding variable.

Next, perform the proper order of operations to find the value of the expression. (PEMDAS)

In math expressions, this is the order in which to calculate from left to right:
1. Parentheses 
2. Exponents
3. Multiplication
4. Division
5. Addition
6. Subtraction

Note: If an expression has only multiplication and division, solve from left to right.
If an expression has only addition and subtraction, solve from left to right.

Example

Find the value of the expression if x= 4 and y = 6.

xy ÷ 8

Solution

Insert the values of x and y into the equation.
Since x = 4 and y = 6, the equation will look like this:

4 x 6 ÷ 8

Next, perform the Order of Operations. 
Parentheses: None
Exponents: None
Multiplication: 4 x 6 ÷ 8 = 24 ÷ 8 
Division: 24 ÷ 8 = 3
Addition: None
Subtraction: None

The value of this expression is 3.

Pre-requisite Skills

Basic math operations (add/subtract/multiply/divide)