1. Warm Up
Simplify.
 3  1
2. 87  15  5
3. 6(9 + 2) + 7
4. 35  7  5 24 84 73 25

2. Vocabulary
variable
constant
algebraic expression
evaluate

3. A variable is a letter or symbol that represents a quantity that can change.
A constant is a quantity that does not change.

4. Algebraic Expressions NOT Algebraic Expressions
An algebraic expression contains one or more variables and may contain operation symbols. So p  7 is an algebraic expression.
Algebraic Expressions
NOT Algebraic Expressions
150 + y
85 ÷ 5
35  w + z
 5
To evaluate an algebraic expression, substitute a number for the variable and then find the value.

5. You can write multiplication and division expressions without using the symbols  and .
Instead of . . .
You can write . . .
x  3
x  3
x(3) 3x 35 y
35 ÷ y
When you are multiplying a number times a variable, the number is written first. Write “3x” not “x3.” Read 3x as “three x.”
Writing Math

6. Examples
Evaluate 16 + b if b = 25

7. Examples
Evaluate x – y if x = 64 and y = 27

8. Example
Evaluate 5t + 4 if t = 3