My car consumes 9 liters of petrol in 100km. Unfortunately, there is a leak in the tank which causes me to take 10ml of gasoline per kilometer. I filled 50 liters of gasoline, how many kilometers do I have to travel to empty my tank?

the car actually consumes

9/100 + 10/1000 = 1/10 L/km
so, you can drive
50L * 10km/L = 500 km

I guess that would also depend on the mixture of petrol and gasoline you use ...