Two trains leave the same station headed in opposite directions. After 4 hours the trains are 120 miles apart. If train A travels twice as fast as train B, how fast does train A travel?

80mph

Step-by-step explanation:

Firstly in a problem like this, I would divide 120 by 3, making 40. Now I knwo that I can use 40 and 80 because it adds up to 120 and 80 is double 40.

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.