Solve the proportion by cross-multiplying.
39/9=x/2
x= 8 2/3
Solve the proportion by cross-multiplying.
26:x=117:9
x=2
Solve the proportion by cross-multiplying.
74:31=2:x
x=31/37
Solve the proportion by cross-multiplying.
x/3=1351/7
x=579
What does a linear graph look like?
A straight line!
Rosa drove 175 miles to visit her grandparents. How many kilometers did she travel?
1 mi = 1.61 km
1 km = 0.62 mi
281.75 kilometers
Franco weighs 165 pounds. What is his mass in kilograms?
1 kg = 2.2 lbs
1 lb = 0.45 kg
74.25 kg
Hector needs to refill his lawn mower gas tank. The tank holds 4.2 liters of gas. How many gallons of gas does the tank hold?
1 L = 0.26 gal
1 gal = 3.79 L
1.092 gallons
How can I tell if a relationship is proportional by looking at its graph?
The graph is linear and goes through the origin.

Does the graph show a proportional relationship? Why or why not?
Not proportional - it is not linear

Does the table show a proportional relationship? Why or why not?
Proportional - there is a common ratio of y/x

Does the table show a proportional relationship? Why or why not?
Not propotional - 35/25 is not equal to 50/45
Kim learned in her science class that every 2 minutes she spends in the shower, she uses 17 gallons of water. This rate is constant.
Identify the constant of proportionality for the number of gallons used to the time in minutes.
k=17/2=8.5

Does the graph show a proportional relationship? If so, find the constant of proportionality.
Proportional - the common ratio k=4
Francis played tennis for two hours. His activity watch showed that he burned 17 calories every 5 minutes.
Define variables for the number of calories burned and the time Francis played tennis.
Let c = the number of calories burned
Let m = the number of minutes
Determine the unknown value.
k=32 and y=15
x = ?
x=2 2/15
Find the unknown value.
k=7/3 and x=21
y = ?
y=49
Find the unknown value.
k=0.18 and y=450
x = ?
x = 2500
Kim learned in her science class that every 2 minutes she spends in the shower, she uses 17 gallons of water. This rate is constant.
If Kim showers for 4 minutes, how many gallons of water will she use?
34 gallons of water
Francis played tennis for two hours. His activity watch showed that he burned 17 calories every 5 minutes.
Determine the constant of proportionality for the ratio between the number of calories burned and the time Francis played tennis, in minutes.
k=17/5=3.4

Write an equation for y, the number of butterflies, based on x, the number of insects.
y=4/15x

Write an equation for y, the number of euros, based on x, the number of dollars.
y=1.5x
Kim learned in her science class that every 2 minutes she spends in the shower, she uses 17 gallons of water. This rate is constant.
Write an equation to find the gallons used based on the minutes spent in the shower.
g = 17/2m
Francis played tennis for two hours. His activity watch showed that he burned 17 calories every 5 minutes.
Write an equation for the number of minutes spent playing tennis based on the number of calories burned.
m=5/17c
y=12x is the equation for the number of cupcakes I can decorate in x hours.
Interpret the constant of proportionality in this context.
I can decorate 12 cupcakes in each hour.