There are 206 miles left to drive so Tammi would be driving.
In order to determine the miles left to drive, the sum of the total miles driven have to be determined. This figure would be subtracted from the total miles of the trip.
x = total miles of the tip - sum of miles already driven
Sum of miles already driven = 198 + 189 + 105 + 202 = 694
x = 900 - 694 = 206 miles
To learn more about subtraction, please check: https://brainly.com/question/854115