SOLUTION: A student walks and jogs to college each day. The student averages 5km/h walking and 9km/h jogging. The distance from home to college is 8km, and the student makes the trip in 1

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Question 135537This question is from textbook
: A student walks and jogs to college each day. The student averages 5km/h walking and 9km/h jogging. The distance from home to college is 8km, and the student makes the trip in 1 hour. How far does the student jog? This question is from textbook

Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
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A student walks and jogs to college each day. The student averages 5km/h walking and 9km/h jogging. The distance from home to college is 8km, and the student makes the trip in 1 hour. How far does the student jog?
:
Let x = distance jogged
then
(8-x) = distance walked:
:
Write a time equation: Time = dist/speed
:
Walk time + jog time = 1 hr
%28%288-x%29%29%2F5 + x%2F9 = 1
;
Multiply equation by 45 to get rid of the denominators
45*%28%288-x%29%29%2F5 + 45*x%2F9 = 45(1)
9(8-x) + 5x = 45
:
72 - 9x + 5x = 45
:
-4x = 45 - 72
:
-4x = -27
;
x = -27/-4
:
x = 6.75 km jogged
;
:
Check solution: 8 - 6.75 = 1.25 km walked; check using the time equation
1.25/5 + 6.75/9 =
.25 + .75 = 1