Question 586109: Two vans leave at the same time, one headed north, one headed south. The one headed north is 10 km/h faster than the one headed south. In 3 hours, they are 420 km apart.
I think I already have one equation , which would be x=y+10, however, I don't understand how to set the other one.
Answer by stanbon(75887) (Show Source):
You can put this solution on YOUR website! Two vans leave at the same time, one headed north, one headed south. The one headed north is 10 km/h faster than the one headed south. In 3 hours, they are 420 km apart.
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North van DATA:
time = 3 hrs ; rate = x+10 km/hr ; distance = r*t = 3x+30 km
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South van DATA:
time = 3 hrs ; rate = x km/hr distance = r*t = 3x km
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Equation:
distance + distance = 420 km
3x+30 + 3x = 420
6x = 390
x = 65 km/hr (rate of South-bound van)
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x+10 = 75 km/hr (rate of North-bound van)
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Cheers,
Stan H.
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