we can use formula

where
fL is listener frequency
fs is siren frequency
va is the speed of sound in air
vs is police car speed
so, we have



now, we can change it into m/s


now, we can plug it

..............Answer
The correct answer is -b+12
Answer:
tbh i really dont know
Step-by-step explanation:
There is 1000 grams in a kilogram so he had a mass of 5,000 grames in his bag