so we have :
9 dollars for 5 miles ride
12.75 for 8 miles ride
lets have x be the miles
y be the dollars
for maria, the charge is per mile, for 3 miles 12.75-9=3.75
1 mile she will pay 3.75/3=1.25 dollars
the pick up fee is 9-6.25=2.75
the y intercept it is (0,2.75)
which means that in the moment you go in the taxi the cost will be 2.75
and after that you will be charged by the mile