The taxi fare in Gotham City is $2.40 for the first 1/2 mile and additional mileage charged at the rate $0.20 for each additional 0.1 mile. You plan to give the driver a $2 tip. How many miles can you ride for $10? (An explanation would be helpful!)

3.3 miles should be the answer
10 = 2.40 + .2x    - take 2.4 from both sides
7.6 = .2x              - take 2 from 7.6 for the tip
5.6 = .2x              - divide both sides by .2
28 = x
this means that you can pay the taxi drives an additional 28 times with the .20 cents fee and still have 2 dollars left over       
now multiply 28 by .1 miles which is 2.8 miles
add 2.8 miles to .5 miles which equals 3.3 miles