21 Litres @ £1.089 per litre.
So that's 4.6 gallons @ £4.96 per gallon
4.6 * 4.96 = ~£22.80 = ~$45.
Roughly £10 of that has gone straight to the Treasury.
That will last about 10 days of normal driving.
Edit: Just checked and it appears you Americans calculate Gallons incorrectly so it's actually about 5.55 of your Gallons.