To find out how many miles Dante can drive with a full tank of gas, multiply 12 by 22. You will get 264, which is how many miles Dante can drive with a full tank of gas. If you divide 638, the total length of the trip, by 264, the answer is 2.41666. This means that it will take about 2 and a half full tanks of gasoline to get to his cousin. Since he started with a full tank, Dante will have to stop twice to completely refill his tank. The second time he stops, he will only use about half of his tank.
The answer is 2 times, or twice.
Hope this helps :)