
Answer:
See below
Step-by-step explanation:
From noon to 1500 Â is three hours
 train A   then travels  3x  where x = speed in km/hr
 train B  only travels for 2.45 hours and covers
          2.45 ( x + 15)      where x + 15 is its speed in km/hr
    these two values sum to the 300 km distance
3x   +   2.45 ( x + 15) = 300
3x + 2.45 x  + 36.75 = 300
x = 48.3 km/hr    x+15= 63.3 km / hr