The BMW Hydrogen 7 Consumes an Average of 13 $50.0 \mathrm {~L} / 100 \mathrm {~km}$

The BMW Hydrogen 7 consumes an average of 13.7 L/100 km of gasoline (when operating in the gasoline mode) and $50.0 \mathrm {~L} / 100 \mathrm {~km}$ of liquid hydrogen (when operating in the hydrogen mode).
(a) If gasoline costs $\$ 0.90 / \mathrm { L }$ , what is the fuel cost per km in the gasoline mode?
(b) If the hydrogen is produced and processed using electricity that costs $\$ 0.12 / \mathrm { kWh }$ , what is the cost per km in the hydrogen mode?