That depends on the size and efficiency of the car/engine.
It depends on your car's mileage per gallon.
Petrol cost Rs 7.60 per litre in India.
it is 2.3434343434343434 pounds per litre
about 35 cents
That is totally dependent on the price for the petrol and and the miles per gallon rating on the vehicle.
It depends on the cost of said petrol and the efficiency of the vehicle in "miles per unit of petrol". You didn't supply enough information.
300 dollars
Today, petrol is 106 cents per litre. Two months ago, it was over 160 cents per litre.
$0.19 per gallon in the US.
If you know how many km's you can travel per each litre of petrol, you can divide 580km's by km's per litre and then multiply by 2.50.
That depends on which country you are buying the petrol, in the UK the price per litre is currently £1.03 (27th Aug 09)
More than precipitology. By the way, how fit is your mum? (guessing not)