Explanation:
let speed of freight train be x
speed of passenger train = x+6
Passenger train distance = 280 miles
freight train 250 milesthe times taken for these distances is the same
280/(x+6)=250/x
280x=250(x+6)
280x=250x+1500
30x = 1500
x= 50 mph the speed of freight train.
x+6= 50+6 = 56mph = speed of passenger train.