standard_description: Use variables to represent numbers and write expressions when solving a real-world or mathematical problem; understand that a variable can represent an unknown number, or, depending on the purpose at hand, any number in a specified set.
problem_activity: Problem 1
At the candy store, M&Ms and Skittles are sold for $0.50 per ounce. Kevita puts some M&Ms in a bag and then adds 8 ounces of Skittles. The total cost for her bag of candy is $6.50.
Kevita and Mary write the equation
$${0.5(x+8)=6.50}$$
to represent the situation, where
$$x$$
represents the number of ounces of M&Ms.
Kevita says that to solve this equation, you first distribute the
$$0.5$$
through the parentheses to get
$${0.5x+4=6.50}$$
.
Mary says that to solve this equation, you first divide by
$$0.5$$
on both sides to get
$${x+8=13}$$
.
Do you agree with either Kevita or Mary? Why? Finish solving the problem to find out how many ounces of M&Ms Kevita put in her bag of candy.
Problem 2
The taxi fare in Gotham City is $2.40 for the first
$${1 \over 2}$$
mile and additional mileage is charged at the rate of $0.20 for each additional 0.1 mile. You plan to give the driver a $2 tip. How many miles can you ride for $10?
What are two different ways you can solve this problem?
Problem 3
The ages of three cousins are consecutive integers. The sum of their ages is 45. Calculate their ages.
a.   Draw a tape diagram to represent the ages of the cousins.
b.   Let the youngest cousin's age be represented as
$$x$$
years old. Write and solve an equation to find the ages of the cousins.


aligns: no