Sandy is taking a
cab in New York City. The taxi fare includes a base
charge of $2.50 as soon as you enter the cab, plus an
additional $2.50 per mile traveled. If Sandy starts off
with a $20 bill, takes the cab for five
miles, and leaves a $1 tip, how much money will
she be left with? Well let's first just think
about how much this five mile cab ride is going to cost her. So cab-- I'll call
it the cab fare. So it's going to be $2.50 just
when you get into the cab, plus $2.50 per mile. Well she's going
to go for 5 miles-- let me write it this way--
times $2.50 per miles. So the cab fare here is just
going to be $2.50, this $2.50, plus 5 times $2.50. Let's see, 5 times
$2.50, that is $12.50. So this is plus $12.50. $2.50 plus $12.50
is going to be $15. So just the cab fare
is going to be $15. And then Sandy gives a $1 tip. So fare plus tip is going
to be equal to the cab fare $15 plus $1 which
is equal to $16. So then answering the
question, how much money would she be left
with with a $20 bill? Well we could
write her change is going to be, she's going
to give a $20 bill, the fare plus tip
is $16, minus $16. So she's going to have
$4 left in change.