To solve this problem you must apply the proccedure shown below:
1. You have that Jim drove the car 2,718.3 miles for a total mileage of 87,416.
2. Then, to calculate the mileage before last month, you only need to substract the total mileage given in the exercise above and the mileage drove last month, as following:
Therefore, the answer is: 84,697.7 miles.