Atrain leaves little rock , arkansas, and travels north at 70 kilometers per hour . another train leaves at the same times and travel south at 85 kilometers per hour . how long will it take before they are 620 kilometers apart?

distance = rate times time.

Here the distance covered by the first train is (70 km/hr)t (t=# of hours), and that by the second train is (85 km/hr)t.

Add these together and set the sum equal to 620 km:

70t + 85t = 620, or 155t = 620, or 4. It will take 4 hours for the distance between the two trains to increase to 620 km.

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step-by-step explanation:

i took the test: )

step-by-step explanation:

points a and b are equidistant from the desired line, so the line you find by using them will go through point r.

using points other than a and b will give the desired line only if they are equidistant from r. if they are randomly located, the perpendicular line you create will not necessarily go through point r, hence will not be a solution to the problem.