Hi zegroes, first, why do you think this person wanted the answer in litres?
I suppose we often 'guess' what people want so I can't fault you for this.
If you are going to change to litres, why wouldn't you get the total of the two first
i.e. 11gal 3 qu=11.75gal = 3.785412*11.75=44.48L (2dp) U.S. units
I used this site for the unit convertion
http://www.sciencemadesimple.com/volume_conversion.php
how did you get your great big numbers?
ok I just worked out your probable error you had 1 quarts=946.352946 liters BUT this is not litres - it is mL
you must be careful! Otherwise your method would have worked.