SOLUTION: Two trains leave Chicago at the same time and in opposite directions. One is going 120MPH and one is going 130MPH. How long before they are 750 miles apart? Answer: 6 I am no

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Question 619487: Two trains leave Chicago at the same time and in opposite directions. One is going 120MPH and one is going 130MPH. How long before they are 750 miles apart?
Answer: 6

I am not sure my equation is correct.
750/120=6
750/130= 5.7
I rounded up and came to conclusion that 6hr would be the average time. Is this correct? If not whats the equation I need to use. Thank you.
Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!
Train 1:

d = rt

d = 120t

Train 2:

d = rt

d = 130t

--------------------------

So train 1 has traveled 120t miles in t hours and train 2 has traveled 130t miles in t hours.

Since they are going in opposite directions (along let's assume a straight track), they will be 120t+130t = 250t miles apart after t hours.

We want this distance to be 750, so

250t = 750

t = 750/250

t = 3

So in 3 hours, the two trains will be 750 miles apart.