If I am traveling 285 miles per hour how long will it take me to get 3.8 miles
You are given m/h and m and want h
so if we DIVIDE m BY m/h
we get
m / m/h = m x h/m = h (because the m's cancel)
So your answer is
3.8m / (285 m/h) = 3.8 / 285/1 = 3.8 x 1/285 = 3.8/285 = 0.0133333333333333 hr or 48 seconds