petrol calculations

EUREKA~!
i made an interesting discovery just a minute ago from my daddy!
for the past 14mths of my driving, little did i know how a petrol tank functions...
but now! haa! i feel empowered by this knowledge that my dad has jus shared with me! =)

well here is hw it works.
my car has a total capacity of 42litres.
it has already travelled 450km.
the mileage return i got was 13.085km/l.
meaning that for every 1litre of petrol, my car can travel an average of 13km.
dad pumped in 34.39litres of petrol.
which means that the car actually has a remainder of approx. (42-34.39) = 7.61litres

heh. so much for being paranoid that i wont have enough petrol left to travel home from sch jus nw... gee..! -__-
nvm we learn new things everyday dun we? ;)