Question 208160
michaek drove to a friends house at a rate of 40 mph.
 he returned the same route at a rate of 45 mph.
 the driving time for the round trip was 4 hours.
 what was the distance michael traveled?
:
let d = one way distance
:
Write a time equation: Time = {{{dist/speed}}}
:
Go time + return time = 4 hrs
{{{d/40}}} + {{{d/45}}} = 4
Multiply equation by 360 to get rid of the denominators, results:
9d + 8d = 4(360)
:
17d = 1440
d = {{{1440/17}}}
d = 84.7 mi one way
:
then total dist:
2*84.7 = 169.4 mi
:
:
Check solution by finding the times
84.7/40 = 2.1175
84.7/45 = 1.8822
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totaltime 3.9997 ~ 4 hrs