Question 310694
You will need to use the formula D=VT, where D=distance, V=velocity (or speed) and T=time. I will use the subscript 1 or 2 to note which train I am talking about. (V1 = velocity of train 1, V2 = velocity of train 2, and so on)


Write down what you know:


V1=35 km/h
V2 = 65km/h


Total Distance, D = 350 km


The total distance is just the sum of each train's distance, because they started at the same point and travelled in opposite directions.


D = D1 + D2

D = V1*t + V2*t
350 = 35t + 65t
350 = t(35+65)
350 = 100t
350/100 = t
3.5 = t


The trains will be 350 km apart after 3.5 hours.