Answer:
Option C)
is correct
Therefore 
Step-by-step explanation:
Given expression is
To simplify the given expression :

( using the property
)

Therefore 
Therefore option C)
is correct
Therefore the simplified expression is
None of these are correct. the answer is 6 hours, because if the the train is traveling at 30m/h and the distance = 180m than your equation is 30m/180