1. Variables and Expressions As people age, their blood pressure rises. You can approximate a person’s normal systolic blood pressure by dividing his/her age by 2 and then adding 110. How would you write this problem in expression form to solve mathematically.

2. The Language of Algebra Algebra, like any language, is a language of symbols. It is the language of math and must be learned as any other language. You know the symbols of division and addition, so you can write the blood- pressure relationship as: age ÷ 2 + 110 In arithmetic, you could write: □ ÷ 2 + 110 In algebra, we use variables, letters that represent unknown values. In this case the letter x: X ÷ 2 + 110 This is known as a algebraic expression.

3. Expressions like a ÷ 2 + 110 can be evaluated by replacing the variables with numbers and then finding the numerical value of the expression. If Samantha is 18 years old, she could estimate her blood pressure by evaluating the expression, 18 ÷ 2 + 110 a ÷ 2 + 110 = (18) ÷ 2 + 110 = substitute 18 for a 9 + 110 = order of operations, division first 119

4. When reading a verbal sentence and writing an algebraic expression to represent it, there are words and phrases that suggest the operations to use.

5. Translating Word Phrases into Math Expressions While the table on the previous slide gives you an idea about phrases that translate to math operations, being able to identify the key words that determine the operations (+, -, ·, ÷) that will be used to solve problems takes practice.

6. Write an expression for each phrase. 1)a number n divided by 5 2)the sum of 4 and a number y 3)3 times the sum of a number b and 5 4)the product of a number n and 9 5)the sum of 11 times a number s and 3 6)7 minus the product of 2 and a number x 7)6 less than a number x 8)7 times the sum of x and 6

7. Write an algebraic expression to evaluate the word problem: 1)Samantha purchased a 200-minute calling card and called her father from college. After talking with him for t minutes, how many minutes did she have left on her card? Write and solve an expression to represent the number of minutes remaining on the calling card. 2)Jared worked for h hours at $5 per hour. Write an expression to determine how much money Jared earned. How much money will Jared earn if he works a total of 18 hours?

8. Use Order of Operations to simplify each Expression Get your pencil and calculator ready and try these problems.