how much fuel was used?

a plane travelled 12027 kilometres non-stop in 13 hours and 30 minutes. the plane started with 180 kilolitres of fuel, and on landing had enough fuel to fly another 45 minutes. how much fuel was used?

x = kiloliters of fuel used in 13.5 hours
 
y = kiloliters of fuel that would be used in another 0.75 hours
 
x + y = 180
 
x/13.5 = y/0.75 ==> y = 0.75x/13.5
 
x + 0.75x/13.5 = 180
 
x(1 + 3/54) = 180
 
x(19/18) = 180
 
x = 180*18/19