<PRE><B>Question 944311</B>
A motorist made a 200 km trip averaging 50 km/h on a level road and 25 km/h on a mountain road.
 The time spent on the mountain road was 1 hour less than the time spent on the level road.
 How many km of the trip were on the mountain road?
:
Let m = distance on mountain roads
then since the total distance is 200km,
(200-m) = distance on level roads.
:
Write a time equation, time = dist/speed
:
level road time - mountain road time = 1 hr
{{{((200-m))/50}}} - {{{m/25}}} = 1
multiply equation by 50 and cancel the denominators, leaving us with:
200-m - 2m = 50
-3m = 50 - 200
-3m = -150
m = -150/-3
m = +50 km on mountain roads
:
:
Confirm this by finding the time of each, level road: 200-50 = 150 km
{{{150/50}}} - {{{50/25}}} = 
3 - 2 = 1 hr
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