Arthur D. answered 03/02/18
Tutor
4.9
(125)
Forty Year Educator: Classroom, Summer School, Substitute, Tutor
distance=rate*time
320=(r)(2.5)+(r+20)(2.5) 11:00 am to 1:30 pm is 2.5 hours
320=2.5r+2.5r+50
320-50=5r
270=5r
r=270/5
r=54 kph is the speed of the southbound train (answer)
r=54+20=74 kph is the speed of the northbound train

Arthur D.
tutor
You're very welcome, Ray.
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03/03/18
Ray O.
03/02/18