1. Variables and Expressions

2. There are types of expressions
a Numerical expression Contains only numbers and operation symbols.
Ex: x 2
a Variable expression contains at least one variable.
Ex: 7 - a + 2
What is a Variable? A symbol usually a letter that stands for an unknown number

3. Evaluate each expression
x for x = ___________ = ________
80 ÷ c for c = ___________ = ________
7 m for m = ___________ = ________
10 + 2p for p = ___________ = ________
k ÷ 2 for k = ___________ = ________
2 ( y – 3 ) for y = ___________ = ________

4. Writing Variable Expressions
Make a list of ALL the words or phrases you can think of that describes each operation:
ADDITION
SUBTRACTION
MULTIPLICATION
DIVISION

5. ADDITION AND SUBTRACTION

6. USE your list to describe each numerical expression
5 + 8
10 - 4

7. MULTIPLICATION AND DIVISION

8. USE your list to describe each numerical expression
10 × 3
18 ÷ 6

9. Can those same words be used to describe variable expressions?
WORD PHRASE
Variable Expression
The sum of m and 45
22 is more than a number
w less than 55
The product of k and 10
The quotient of r and s

10. Write two word phrases for EACH variable expression.
2. m – n
3. 6x
4. 18 ÷ p

11. Writing Variable Expressions
How can we write a variable expression for each word phrase?
Five plus y ________________
6 times q ________________
2 less than x _______________