Answer
Find out the how many kilometers (x) she can drive on 22 liters of fuel .
To prove
As given
Eliana drove her car 81 km and used 9 liters of fuel .
She assumes her car will continue consuming fuel at the same rate .
9 litres = 81 km

1litre = 9 km
Thus in 1 litre of fuel Eliana drove her car 9 km .
for the 22 litre of fuel .
22 litre = 22 × 9
= 198 km
Therefore 198 km Eliana can drive on 22 liters of fuel.