<PRE><B>Question 76449</B>
 The student averages 5 kmh walking and 9 kmh jogging. The distance from home to college is 8 k, and the student makes the trip in 1 hour. How far does the student jog?
:
Let x = jogging distance; then (8-x) = walking distance
:
Write a time equation; Time = distance/speed
:
Jogging time + Walking time = 1 hr
    {{{x/9}}} + {{{((8-x))/5}}} = 1
:
Multiply equation by 45 to get rid of the denominators:
5x + 9(8-x) = 1
5x + 72 - 9x = 45
5x - 9x = 45 - 72
-4x = -27 
x = -27/-4
x = 6.75 km jogging
:
8 - 6.75 = 1.25 km walking
:
:
Check using time:
6.75/9 + 1.25/5 =
 .75 + .25 = 1 hr


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