Question

A parachutist's rate during a free fall reaches 99

Answer 1

First, you need to convert miles to feet 

99 miles * $\frac{5280 feet}{1 mile}$ = 522720 feet

now you can convert feet per hour to feet per second

$\frac{522720 feet}{1 hour} * \frac{1 hour}{60 minutes} * \frac{1 minute}{60 seconds}$

each unit will cancel out so that when you multiply them together the only units you are left with are feet in the numerator and seconds in the denominator

once it is multiplied, you should get

522720 feet/ 3600 seconds

since you want the feet per second, you want the denominator to equal 1, so to do this, you divide the numerator and the denominator by 3600

$\frac{522720 feet}{3600 seconds}$ / 3600

now you should get your answer of 

145.2 feet per second

to get how many feet after 5 seconds you just multiply 145.2 by 5

145.2 * 5 = 726
the parachutist will fall 726 feet during 5 seconds of freefall

hope this helped!