Answer:

Explanation:
Apparent frequency that is received to the speeder is given as


here we know that

now we have


now the frequency that is received back from the speeder is given as



So difference is the frequency is given as


The van's AVERAGE speed on the way up the hill is
(1/2) (20 + 12) = (1/2) (32) = 16 m/s .
At an average speed of 16 m/s, it travels
(16 m/s) x (8 s) = 128 meters in 8 seconds.
Answer:
- Please see the attached picture for full solution!:)
--------------- HappY LearninG <3 ---------