Since one mile equals 5280 feet, the train has to travel
[tex] 70 \cdot 5280 = 369600 [/tex] feet.
Every second the train travels 35 feet, so it takes the train
[tex] \dfrac{369600}{35} =10560 [/tex]
seconds to cover that distance. Since there are 60 seconds in a minute, to convert seconds in minutes you have to divide by 60:
[tex] \dfrac{10560}{60} = 176 [/tex]
So, it takes 176 minutes to the train to cover that distance.