distance algebra

Question

In one U.S. city, the taxi cost is $ 5 plus $0.50 per mile. If you are traveling from the airport, there is an additional charge of $ 3.50for tolls. How far can you travel from the airport by taxi for $28.50?

Answer 1

So our cost formula is:

 

C = 5 + .5d + 3.5

 

If we set this equal to the 28.5 in our pocket, we get

 

5 + .5d + 3.5 = 28.5

.5d = 20

d = 40

 

So, our answer is 40 miles.  Incidentally, you should be able to see this intuitively as well.  If you subtract the fixed costs from $28.50, you see that we have $20 to spend on mileage, which at $.5 per mile gets you 40 miles.