Distance/time/velocity question pls help?

Question

Frances travels between two places, Akville and Bracktown. She walks half the distance at 5km/h and runs the other half 10km/h. if the total time for her journey is 3 hours, what is the distance from Akville to Bracktown?

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Answer 1 · 2018-01-31T00:15:01

#x=20# km

.

Let's let the distance be #x#.

If she walks half of it at #5# km/h then the amount of time it takes her to walk that half is:

#(x/2)/5=x/10# hours

Because she runs the other half at #10# km/h then the amount of time it takes her to run that half is:

#(x/2)/10=x/20# hours

Now, we can say:

#x/10+x/20=3#

#(3x)/20=3#

#3x=60#

#x=20# km