The maximum number of miles that he can drive the car will be 300 miles.
Step-by-step explanation
Suppose, the number of miles he can drive the car is
The car rents for $35 per day plus $0.21 per mile. So, the total cost for
miles

As he can spend no more than $98 per day, so.....

Thus, the maximum number of miles that he can drive the car will be 300 miles.