If you drive for an hour, you have driven 45 miles. If you have driven for a longer or shorter time, you have driven more or less, respectively. You have to specify the amount of time to get the answer.
12 minus 6.8= 5.2
Six more hours.
MPH equals the miles driven, divided by the time it takes to drive those miles (units of time is hours, or minutes divided by 60).
The answer is in the "Miles per hour" (Mph) you drove. If you drove 40 Mph, then in one hour you would have driven 40 miles. Therefore, in five hours, at the constant speed of 40 Mph, you would have drive 200 miles.
You have driven 55.9234 miles.
If you drive for an hour, you have driven 45 miles. If you have driven for a longer or shorter time, you have driven more or less, respectively. You have to specify the amount of time to get the answer.
WIf you drive x miles in reverse, you could have driven the same x miles forward - in "Drive". The distance between A and B remains the same as the distance between B and A - do it that way or some other way.
miles_left = 21.0 - 2.6 = 18.4
By definition, if I drive at 40 miles per hour for one hour (equivalent to 60 minutes) then I have driven for 40 miles; as for the number of miles you drove, I have no idea.
12 minus 6.8= 5.2
Six more hours.
About 350 miles that can be driven in about 5.5 hours.
If you average 60 mph, you can drive 660 miles in 11 hours.
That depends on the miles driven and the economy of the vehicle.
You can safely drive any car 3,000 miles before changing the oil/filter if it is driven normally. I drive normally and change my oil/filter every 5,000 miles. Follow your owner's manual recommendation.
That depends on how fast the car is being driven and you have not told us that.