Answer:
Step-by-step explanation:
We'll make a table for this since we have 2 different trains for which we have formulas. We'll use the distance = rate * time formula, but we have to use it twice because we have 2 trains, then we have to come up with an equation that incorporates both of the distances of the 2 trains to come up with a time. Easy.
d = r * t
East train
West train
Now we can fill in. We know that the rate of the east train is 105 and the rate of the west train is 85, so we fill that in:
d = r * t
East train 105
West train 85
The time is what we are looking for, so that is the unknown for each train:
d = r * t
East train 105 t
West train 85 t
Since the formula is d = rt, we will multiply the rates of each times the time of each and fill in accordingly:
d = r * t
East train 105t 105 t
West train 85t 85 t
Here's an illustration to the best of my abilities in this forum:
<------------------------------|----------------------->
85t 105t
|----------------------456 miles-------------------|
The illustration is supposed to show you that the distance between the trains (456 miles) is found by adding the 2 distances together and solving for t:
85t + 105t = 456
190t = 456 so
t = 2.4 hours
