Interpreting Variables EQ: How do I interpret the variable from a word problem? (Standard A.SSE.1)

Review Last class, we practiced writing expressions from word problems. Today we will work on interpreting the variable in context of the problem.

What is the variable? Given an expression or word problem, how can you determine what the variable represents? Questions to ask yourself: What is the problem asking me? What information do I know from this problem? What is the unknown variable? What am I trying to solve for?

Creating Expressions Practice Directions: Write the expression that represents the statement. Example 1: Joan’s temperature increased by 3 degrees What is the unknown variable? Joan’s temperature Answer: t + 3 Example 2: Six minutes less than twice Bob’s time Bob’s time Answer: 2b – 6

You Try! Example 3: Twice Betty’s age plus 5 Directions: Write the expression that represents the statement. Example 3: Twice Betty’s age plus 5 Example 4: 3 less than 12 times John’s age

Expressions from Word Problems Example 5: Sara and her friends had dinner at a Spanish restaurant that charges $6 per tapas. All of them shared several tapas. The total bill included taxes of $4.32. Write an algebraic expression that represents the total cost of the dinner. What do I know? What is the unknown variable? Answer: 6p + 4.32 What does the variable, p, represent? p represents the number of tapas ordered.

Expressions from Word Problems Example 6a: Andre purchased a can of tennis balls and received a 25% discount. Write an algebraic expression to represent the total cost of the tennis balls. What do I know? What is the unknown variable? Answer: t – .25t What does the variable, t, represent? t represents the cost of the can of tennis balls

Expressions from Word Problems Example 6b: What if Andre purchased 10 cans of tennis balls and still received the same 25% discount. How would your expression from part a change? Answer from part a: t – .25t

Expressions from Word Problems Example 6c: How would your expression from part b change if Andre had to pay a shipping cost of $5.99? Answer from part b: 10t – .25(10t)

You Try! Example 7: Gavin agrees to buy a 6-month package deal of monthly gym passes, and in turn receives a 15% discount. Write an algebraic expression to represent the total cost of the monthly passes with the discount.