To calculate miles per gallon of gas, we take the 478 miles the motorcycle travels and divide it by the amount of gallons in a full tank of gas, 12 gallons.  478/12 = 39.83, or 39.8 when rounded to the tenths place

For the price, we take the 12 gallons and multiply it by the amount that one gallon costs, $4.25.  (12)(4.25) = 51

First we determine how many gallons it will take to travel 3,149 miles with this particular car: 3,149/31=101.58 gallons. The cost of gas per gallon= $3.69, therefore 101.58x$3.69= $374.83.

We divide 1,457 miles by 47 miles per gallon to find that 31 gallons of gas are needed for the road trip.

We then multiply the gallons of gas by the cost per gallon to find: 

31 x 4.13 = 128.03

First, we need to convert the 1 hour into minutes in order to keep consistent with units -- so, the car averages 32 miles per 60 minutes.  Then, a ratio can be set up to solve this: 32 mi / 60 min = x mi / 20 min. Cross multiplying and dividing, we get x = 10.667 miles.  Rounding to the nearest tenth, this becomes 10.7 miles. 

First, find the total amount of gas necessary for the trip. 6363/63 = 101 gallons (easy to see as 63 * 100 = 6300 + 1 * 63 = 6363). Then multiply the number of gallons by the price per gallon of gasoline, 5.05 * 101 = $510.05 and is your answer (again, easy to see when 5.05 * 100 + 1 * 5.05).

Remember that distance/time=rate, so then:

x/15 = 65

x = 65 * 15

x = 975 miles

The general equation is distance = rate x time.  In addition, the distance upstream is the same as the distance downstream.  So, r_up x t_up = r_down x t_down.  Be sure to convert minutes to hours because the rate is given in mph (miles per hour).

Therefore, (r + 3)(1/2) = (r – 3)(1) and solve for r.

Note, r + 3 is the downstream rate and r – 3 is the upstream rate

In order to get the total amount of gas used in Sarah’s trip, first find how much gas was used on the highway and add it to the amount used in the city. Highway gas usage can be found by dividing

 and city usage can be found by dividing

.

Then we add these two answers together and get  

We know that the rate of a car can be written in the equation:

This means that you need the distance and time of your total trip. We know that the trip was a total of  or  hours. The distance is easily calculated by multiplying each respective rate by its number of hours, thus, you know:

Therefore, you know that the rate of the total trip was:

Recall that the basic form for a rate is:

, where  is generically the amount of work done. Since the question asks for the answer in gallons per hour, you should start by changing your time amount into hours. This is done by multiplying  by  to get .

Thus, we know: