When a sound source is moving toward the observer, the observer will hear a higher pitch. this is due to

Doppler effect

Explanation:

Doppler effect is the effect produced by a moving sound source in which there is a higher pitch for observers towards whom the source is approaching and lower pitch for observers from whom the source is receding.

ι вєℓιєνє ιт ιѕ тнє fιяѕт ¢нσι¢є(α.)

нє ѕнσυℓ∂ ѕмιℓє ρσℓιтℓу αи∂ ѕρєαк тσ тнє ρєяѕσи ωнσ ιѕ ιитєяяυριиg αfтєя тнє ∂ιѕ¢υѕѕισи

нσρє ι ¢συℓ∂ нєℓρ.

the total distance traveled by the car is

30km + 49km = 79 km .