Train 1 travels at speed = X
Train 2 travels at speed X - 19
Their speed of approach is: 663 kilometers / 3 hours = 221 kilometers per hour.
Now the sum of their speeds = 221 kilometers per hour
x + x-19 = 221
Simplify:
2x-19 = 221
Add 19 to both sides:
2x = 240
Divide both sides by 2:
x = 120
Train 1 travels at 120 kilometers per hour.
Train 2 travels at 101 kilometers per hour.