1. Lesson 1
Introductory Algebra
The Four Operations

2. Warm-Up
6 × 7
56 ÷ 8
114 – 96

3. The Four Operations Target:
Find values of expressions involving addition,
subtraction, multiplication and division.

4. Vocabulary
Numerical Expression: Combinations of numbers and operations.
Order of Operations: Rules to follow when evaluating an expression with more than one operation.

5. Order of Operations Multiply and divide from left to right.
Add and subtract from left to right.

6. Example 1 Find the value of 5 × 8 – 12 ÷ 3.
Multiply and divide first. 5 × 8 – 12 ÷ 3 = 40 – 4
Subtract. 40 – 4 = 36

7. Example 2 Find the value of 20 + 16 ÷ 4 – 2 × 9.
Multiply and divide first ÷ 4 – 2 × 9 = – 18
Add and subtract left to right – 18 = 24 – 18 = 6

8. Example 3 Saul’s mom and dad took him to a basketball game for
his birthday. He was allowed to bring four friends with
him. His parents bought $24 tickets for each of the five
boys so they could sit close to the court. The parents’ tickets
cost $10 each. Find the total cost of the game tickets.
Write the problem. $24 × 5 + $10 × 2
Multiply first. $24 × 5 + $10 × 2 = $120 + $20
Add. $120 + $20 = $140
It will cost $140 for the group to go to the game.

9. Exit Problems
6 + 9 ÷ 3 – 1
4 × 5 – 2 × 3
8.8 ÷

10. Communication Prompt
Why do you think mathematicians developed an order of operations for us to follow?