The tank of a car was 5/6 full at the start of a journey. after driving 92 km, it was only 5/8 full?

There is a source of ambiguity in the phrase "... and showed that 10 liters of gas is used."
1) Did it show that 10 liters of gas were used in total
or
2) Did it show that 10 liters were used during the 92 km ride?

The distance travelled is irrelevant in both interpretations.

In the 1st reading it is also irrelevant that the fuel tank was 5/6 full. It only matters that 5/8 are left over and 10 liters were used, which means that 3/8 relate to 10 liter. 1 Liter is then 3/80 and as 80/80 represents the volume of the fuel tank. Thus 80/3 = 26.666...Liter is the volume of the tank.

Now for the 2nd interpretation of the task: Here the difference between the filling level at the start of the journey and at the end relates to 10 liters.
5/6 - 5/8 = 10 L. Find a common denominator
(5/6 times 4/4) - (5/8 times 3/3) equals 20/24 - 15/24 = 5/24 relates to 10L.
1/24 relates then to 2L. The volume of the fuel tank is then 2 times 24 = 48 Liter.