The rate of the car rental company charges is $19 per day or any fraction thereof.
⇒ It charges $19 even if you are using for a min, an hour or a day for that day.
To rent a car for 6.4 days, Mr. Aronsohn will need to pay for 7 days.
$19 x 7 = $133
Answer: It will cost $133 to rent the car.