Have you ever thought your airline ticket cost too much?

First of all, the drag force on the plane is given by

$F_d = \frac12 C_d \rho v^2 A$

The work done to fight friction in the whole cross-country flight is then

$W_d = \int F_d dx = L\times\frac12 C_d \rho v^2 A$

and the total amount of energy we need from the fuel is $E_\text{fuel} = W/\eta$ . Plugging all the numbers in, and recognizing $A = 9\pi$ , we find that the total amount of energy required is $E_\text{fuel}\approx 2.577\times10^{12}$ Joules.

To get the total amount of fuel we need, we use the density of the fuel, and the energy density of the fuel to convert this into a volume $V_\text{fuel} = E_\text{fuel} \times \rho_\text{fuel} \times \frac{1\text{ m}^3}{1000\text{ L}} \approx 71239.6~\text{ L}$ .

The cost of the fuel is thus $\$0.75 \text{ per L} \times V_\text{fuel}\approx \$53893.4$ . The salary of the crew is $6\text{ crew}\times \$20\text{ per hr}\times 5\text{ hr}$ , thus the total cost of running the flight is $c = \$54029.7$ .

The revenue from operating the flight is simply the ticket price times the number of passengers which is $r = \$300\times189=56700$ .

The percent of the ticket prices that goes into profit is thus $100\times\left(1 - c/r\right) = 4.71\%$