SOLUTION: Ok, so town A and town B are 100 miles apart. Car A is leaving from town A and traveling 60mph, and car B is leaving from town B and traveling 50mph. How long before they collide

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Question 110384: Ok, so town A and town B are 100 miles apart. Car A is leaving from town A and traveling 60mph, and car B is leaving from town B and traveling 50mph. How long before they collide? I know it has something to do with the D=r*t formula...I'm just not sure how to figure this one out. Thanks!
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
They leave at the same time and collide at the same time, so
If I writet+=+d%5BA%5D%2Fr%5BA%5D and t+=+d%5BB%5D%2Fr%5BB%5D, then
t is the same for both, and I can write d%5BA%5D%2Fr%5BA%5D+=+d%5BB%5D%2Fr%5BB%5D
and r%5BA%5D+=+60, r%5BB%5D+=+50, so
d%5BA%5D%2F60+=+d%5BB%5D%2F50
And I know d%5BA%5D+%2B+d%5BB%5D+=+100, so I can say
d%5BB%5D+=+100+-+d%5BA%5D
Now I have d%5BA%5D+%2F+60+=+%28100+-+d%5BA%5D%29+%2F+50
50%2Ad%5BA%5D+=+60%28100+-+d%5BA%5D%29
50%2Ad%5BA%5D+=+6000+-+60%2Ad%5BA%5D
110%2Ad%5BA%5D+=+6000
d%5BA%5D+=+54.5454
t+=+d%5BA%5D+%2F+r%5BA%5D
t+=+54.5454+%2F+60
t+=+.90909hrs
.90909hrs x 60min/hr = 54.5454min
.5454 min x 60sec/min = 32.7272 sec
So, the cars will collide in 54 min 33 sec approximately