Sewanhaka High School
Math 8
Name:__________________________
Mrs. Lidowsky, Principal
Mr. Long, Teacher
Per:____
Date:_____________________
H.W. #22: Ditto
DO-NOW #22: Answer the following questions:
Express each rate as a unit rate:
1) $17.40 in 3 hours =
2) 400 miles per 10 gallons =
3) Champions Sporting Goods Store is having its annual clothing sale. The chart below displays the discounts. Alex
buys a pair of sneakers with a price of $48.95, and a tank top with a price of $16.95. There is no sales tax. What is
the final cost of Alex’s purchase?
If your total
You get
merchandise
this
price is…
discount:
$25 or under
20%
$25.01 - $50.00
25%
$50.01 - $75.00
30%
$75.01 - $100.00 40%
$100.01 or over
50%
4) Find the slope of the line that passes through the points M(-2, 3) and N(7, -4)
Topic: Expressions and Equations
Main Idea: Equations in y = mx form
Aim:
Recall
How would you find the slope of the graph at the right
with the given points?
How would you solve the equation: m =
y
in terms of y?
x
Use the table to determine if there is a proportional linear relationship
between the biking time and the money raised.
Notes
Recall
Definition:
Notes
This ratio of
$10
is called a direct variation because when the
1hour
ratio of the two variable quantities is constant, a proportional
relationship exists. This constant ratio is also called the constant of
variation or constant of proportionality (or simply put, it is called
slope). For direct variation, we say y varies directly with x.
Use the previous table to find the rate of change. Then
write an equation in y = mx form to represent the situation.
The amount of money Robin earns while babysitting
varies directly with the time as shown in the graph.
Determine the amount of money Robin earns per hour.
Two minutes after a skydiver opens his parachute, he has
descended 1,900 feet. After 5 minutes, he descended
4,750 feet. If the distance varies directly with time, at
what rate is the skydiver descending?
A cyclist can ride 3 miles in 0.25 hour. Assume that the
distance biked in miles y varies directly with time in hours
x. This situation can be represented by y = 12x. Graph
the equation. How far can the cyclist ride per hour?
Drill: Answer the following questions. Show work.
1)
2) A new compact car can travel 288 miles on nine gallons of gas. The distance driven in miles y varies directly with
the number of gallons of gas x. The situation can be represented by the equation y = 32x.
a) Graph the equation.
b) How many miles per gallon does the car use?
c) The distance y traveled by a hybrid car using x gallons of gas can be
represented by y = 42x. Which car gets the better gas mileage?
Explain.
Summary: