Consider the ratio of miles driven to the average miles per gallon.
B
b
Think about the total miles driven in a year.
C
c
Use the formula you came up with.
A
a
g=x/m
B
b
c=x/m* p
C
c
$ 32.96, see solution.
Practice makes perfect
a
If the car is driven x miles per year and it drives m miles per gallon, then the number of gallons g has to be equal to x divided by m.
g=x/m
b
If we multiply the number of gallons used g by the average price p, we get the total cost c.
c=g* p
However, we have previously defined the number of gallons as xm, so if we replace g with this expression we get the following equation.
c=x/m* p
c
We will make use of the formulations that we came up with in the previous question. First we will calculate the yearly gas cost c for each of the cars. Then we can convert this number to a weekly cost by dividing c with the number of weeks in a year, which is 52.
Car A
Let's substitute the values for Car A into the formula.
The yearly cost for Car B is about $1285.71. If we divide this with 52, we get the weekly cost.
1285.71/52≈ $24.73
Comparison
Car A costs $ 57.69 per week, and Car B costs $24.73 per week. Let's calculate the difference!
$57.69-$24.73=$ 32.96
This means that Car A costs $32.96 more than Car B per week.
