1. Variables and Expressions
1.3

2. Vocabulary
Algebra: Branch of mathematics that uses symbols such as variables Variable: A letter or symbol used to represent an unknown value. Example: x, y

3. Vocabulary
Algebraic Expression: An expression containing at least one variable and at least one operation. Example: 4-x, 5m +6, ab Defining a Variable: Choosing a variable to represent an unknown quantity

4. Translate each phrase into an algebraic expression
Identify key word for the operation
Define your variable
Translate from left to right

5. Key Words for Operations
Add
More than; sum of; greater than; added to; increased by,
Subtract
Less than; fewer than; subtracted from; minus; difference of; decreased by
Multiply
Times; product of; multiplied by
Divide
Divided by; quotient of;
Order is always left to right EXCEPT words with “than”

6. Ex 1: Three dollars more than the cost of a sandwich
more than : add and switch order
C= cost of sandwich
3+c but need to switch order because of the word than!! Answer: C+3

7. Ex 2: Five points more than the points scored by field goals if each field goal is worth 3 points.
More than: add and switch order Each goal is worth 3 points: multiply by 3
f= field goals
5+3f but because it says the word than switch the order. Answer: 3f +5

8. Substitution Property of Equality
If two quantities are equal, then one can be replaced by the other.

9. Evaluate: if x=3, y=4, z=7
Ex 3: 6y-4x
Ex 4: 5z+(x+4y)-15

10. Evaluate: if x=3, y=4, z=7
Ex 5:

11. Example 6:
Suzanne Middle School sold tickets for a school play. The price of an adult ticket was $3, and the price of a student ticket was $1.
Write an expression for the total amount of money collected.
Suppose 70 adult tickets and 85 student tickets were sold. How much was collected?

12. Homework
Page (12-37, 39, 40)