Answer:
2 minutes
Step-by-step explanation:
The front of the train enters the tunnel and travels 1 km before the rear of the train enters the tunnel. Thus, the total distance traveled by the front of the train is 2 km, and this is covered in a certain number of hours:
Since distance = rate times time, time = distance / rate. In this particular case we have:
2 km
time = distance / rate = ------------------- = (1/30) hr
60 km/hr
(1/30) hr converts to 2 minutes, since 1 hr = 60 minutes
If the denominator does not equal 0, the equivalent expression of
is 

<h3>How to determine the equivalent expression?</h3>
The expression is given as:

Divide 14 by 7

Apply the law of indices

Evaluate the differences in the exponents

Hence, the equivalent expression of
is 
Read more about equivalent expressions at:
brainly.com/question/2972832
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I think the answer for this question is the second one