A University of Florida student earns $15 per day delivering advertising brochures door-to-door, plus 75¢ for each person he interviews. How many people did he interview on a day when he earned $57?

15 + 0.75x = 57

-15 - 15

0.75x = 42

0.75x/0.75 = 42/0.75

x = 56 people

The student interviewed 56 people on the day he earned $57

If the student earned $57 in that given day to find number of people interviewed we first subtract the daily rate of $15 from $57 then we divide the answer by 75c to get number of people interviewed which is 56