Answer:
14.4
Step-by-step explanation:
To find 40 percent of 36, here's how I do it. Just divide 36 by one hundred (move the decimal point two times to the left), giving you 0.36. Then multiply that by 40, and you get 14.4! Of course, there are multiple ways to do it, but that's just mine. If it doesn't work for you, try and search some formulas.
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