options: Use proportional relationships to solve multistep ratio and percent problems. Examples: simple interest, tax, markups and markdowns, gratuities and commissions, fees, percent increase and decrease, percent error.

Recognize and represent proportional relationships between quantities.

Compute unit rates associated with ratios of fractions, including ratios of lengths, areas and other quantities measured in like or different units. For example, if a person walks 1/2 mile in each 1/4 hour, compute the unit rate as the complex fraction 1/2/1/4 miles per hour, equivalently 2 miles per hour.
problem_activity: Problem 1
For Simon’s birthday, he and his family go out to eat at a restaurant.
a.   The amount of tax is $3.40, which is 5% of the food bill. How much was the food bill not including the tax?
b.   If Simon wants to leave a 20% tip on the amount of the food bill before tax, how much should he leave for a tip?
c.   What is Simon’s total bill including tax and tip? What percent of the food bill is this?
Problem 2
Emily has a coupon for 20 percent off of her purchase at the store. She finds a backpack that she likes on the discount rack. Its original price is $60, but everything on the rack comes with a 30 percent discount.
Emily says, “
Thirty percent and twenty percent make fifty percent, so it will cost $30.
”
Is Emily correct? Explain your reasoning. In your explanation, if you disagree with Emily, find the price she will pay for the backpack.
Problem 3
In order to make money, a store marks up its prices by 25% from the warehouse prices. Let
$$p$$
represent the price at which the store gets its merchandise from the warehouse, and let
$$s$$
represent the price the store sells the merchandise for after the markup.
a.   Write an equation to determine the selling price,
$$s$$
, based on the warehouse purchase price,
$$p$$
.
b.   Create a table showing possible pairs of solutions to the equation.
| **                Warehouse price (                                 $$p$$                                )               ** | **                Selling price (                                 $$s$$                                )               ** |
|-----------------------------------------------------------------------------------------------------------------------------|---------------------------------------------------------------------------------------------------------------------------|
|                                                                                                                             |                                                                                                                           |
|                                                                                                                             |                                                                                                                           |
|                                                                                                                             |                                                                                                                           |
|                                                                                                                             |                                                                                                                           |
c.   Create and label a graph for your table.
d.   Interpret the points
$$(0, 0)$$
and
$$(1, r) $$
from the graph in context of the situation.


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