SOLUTION: Given: d = rt, where "d" is distance, "r" is rate, and "t" is time. Two trains on the same track, initially 648 miles apart, leave from their positions simultaneously. T

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Question 874286: Given: d = rt, where "d" is distance, "r" is rate, and "t" is time.
Two trains on the same track, initially 648 miles apart, leave from
their positions simultaneously. They are on a head-on collision
course. One train is traveling 35 mi/hr and the other is traveling
85 mi/hr. What is the length of time to impact?

Answer by josgarithmetic(39620) About Me  (Show Source):
You can put this solution on YOUR website!
More generally, two trains initially m miles apart start traveling toward each other simultaneously. One is going r mph and the other s mph. How much time to meet?

The unknown variable is t, in:
rt%2Bst=m, because the sum of their distances traveled will be m when they meet, or collide.

t%28r%2Bs%29=m
highlight%28t=m%2F%28r%2Bs%29%29.
Substitute the values to find that of t.