<PRE><B>Question 909215</B>
If a motorist drove 150 miles on country roads before driving 50 miles on mountain roads.
 The rate of speed on the country roads was three times the rate on the mountain roads.
 The time spent traveling the 200 miles was 5 hours.
 Find the rate of the motorist on the country roads.
:
let s = speed on the mtn roads
then
3s = speed on ctry roads
:
Write a time equation; time = dist/speed
:
mtn drive time + ctry drive time = 5 hrs
{{{50/s}}} + {{{150/(3s)}}} = 5
multiply equation by 3s
3s*{{{50/s}}} + 3s*{{{150/(3s)}}} = (3s)5
cancel the denominators and you have
3(50) + 150 = 15s
300 = 15s
s = 300/15
s = 20 mph on the mtn 
then 
3(20) = 60 mph on country roads
:
:
Check this find the actual time at each speed
50/20 = 2.5 hrs
150/60 = 2.5 hrs
-------------------
total time: 5 hrs</PRE>