Michael drove to a friend’s house at a rate of 40 mi/h. he returned by the same route at a rate of 45 mi/h. the driving time for the round trip was 4 h. what is the total distance michael traveled?

Distance = rate * time

distance = 40 * t
return trip distance = 45 * (4 - t)

Since distance is the same, then
40 * t = 45 * (4 -t)

40t = 180 -45t
85t = 180
t = 180 / 85
t =  2.1176470588 hours
return trip 4-t =  1.8823529412 hours

distance = 40 * 2.1176470588 =
d =   84.7058823529

distance = 84.7 miles (rounded)
So, the TOTAL DISTANCE = 2 * 84.7 = 169.4 miles

For a double-check we'll use the return trip
d = 45 *   1.8823529412
distance = 84.7058823529
Correct!!!

3.64 deaths an hour.