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
 What is the unknown variable?
 Bob’s time
 Answer: 2b – 6
You Try!
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.