If Rachel jobs for awhile at 8 kmh and then walks at 5 kmh s

If Rachel jobs for awhile at 8 km/h and then walks at 5 km/h, she travels 23 km. If she reverses the amoun of time spent jogging and walking, she travels 6 km farther. Find her total travelling time.

Solution

23 km trip:
8x + 5y = 23
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29 km trip
5x + 8y = 29
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Modify the two equations to set them up for elimination:
40x + 25y = 115
40x + 64y = 232
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39y = 117
y = 3 hrs
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Substitute into 8x + 5y = 23 to solve for \"x\":
8x + 5*3 = 23
8x = 8
x = 1 hr
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Total time: x + y = 1+3 = 4 hrs