This is a SHRINKING GAP question.

Since the trains are traveling in OPPOSITE directions, we ADD the two speeds.
70 mph + 50 mph = 120 mph
So, the gap is shrinking at a rate of 120 mph

time = distance/rate
= (300 miles)/(120 mph)
= 30/12
= 5/2
= 2.5 hours

Answer: 2.5

Cheers,
Brent

1. Shrinking gap rate: 70mph + 50mph = 120 mph rate they are traveling towards each other
2. Time: D= rt --> 300miles/120mph = 2.5 hours till they meet

The trains start 300 miles apart. Since we know train A is traveling 70 mph and train B is traveling 50 mph they are getting 120 miles closer to each other per hour or 2 miles per minute.
Letting x equal the amount of hours we know then that 120x = 300; Therefore x = 2.5.

If they asked for the amount of minutes, the equation 2x = 300 can be used as well.

Hope this helps.

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