The car traveled 80 km. The car engine developed an average power of 40 kW and consumed 14

The car traveled 80 km. The car engine developed an average power of 40 kW and consumed 14 liters of binsin. What is the average speed of the car if the efficiency of its engine is 30%?

η = (Ap. / Az.) * 100%.
Ap. = N * t, N – power (N = 40 kW), t – time (t = S / Vav, S – path (S = 80 km), Vav – speed).
Az = q * m, q – beats. heat of combustion. gasoline (q = 44 MJ = 44 * 10 ^ 6 J / kg), m – mass (m = ρ * V, ρ – density (ρ = 710 kg / m³), V – volume (V = 14 l = 14 dm³ = 0.014 m³).
η = ((N * S / Vav) / (q * ρ * V)) * 100%.
0.3q * ρ * V = N * S / Vav.
Vav. = N * S / (0.3q * ρ * V) = 40,000 * 80,000 / (0.3 * 44 * 10 ^ 6 * 710 * 0.014) = 24.39 m / s (87.8 km / h).