Answer:
Rate of passenger train is 42 mph
Step-by-step explanation:
Let the rate of the passenger train be x
Mathematically;
time = distance/speed
We have the time equal in this case
Rate of freight train is 30 mph slower
So if the rate of passenger train is x mph, rate of freight will be x + 30 mph
Thus, mathematically, we have ;
120/x + 30 = 70/x
70(x + 30) = 120 * x
70x + 2100 = 120x
120x-70x = 2100
50x = 2100
x = 2100/50
x = 42 mph