Answer
The mass of the fuel is $119,202.048 kg$
Work Step by Step
First we must convert the units of $L$ into units of $cm^{3}$ because we will use the density of the fuel (i.e. 0.768 g/cm^3) to determine the mass of the fuel.
$ {155211 L}\times\frac{1000 cm^{3}}{1 L} = 155211000cm^{3}$. Now we can take our unit of volume and multiply it by the density of the fuel; $155211000 cm^{3} \times 0.768 \frac{g}{cm^{3}} = 119,202,048 g$. Lastly we must convert the units of g into kg because the question asks for the mass in kilograms; $119,202,048 g\div1000= 119,202.048 kg$