Two trains leave the station at the same time, but are headed in opposite directions. one train travels at 70 mph and the other train travels at 80 mph. after hours the trains will be 600 miles apart.

4 hours

Step-by-step explanation:

Given: Two trains leave the station at the same time, but are headed in opposite directions. One train travels at 70 mph and the other train travels at 80 mph.

To Find: After how many hours the trains will be 600 miles apart

Solution:

Speed of first train =

Speed of second train =

As trains are heading in opposite directions,

Relative speed of trains =

                                        =

Total distance to be travelled =

Total time taken =

                           =

                           =  

After 4 hours the trains will be 600 miles apart

since proposition states that a number is greater than 25, if is true then the number must actually be greater than 25.

this implies that all possible options, except 24, can be accepted