Distance 1 = 1662 km
Time T= 3 hours
Distance 2= 2142 km
Time T=3 hours
Also
V1 = Plane velocity
V2= Air velocity
Then
Distance1/T = V1 - V2
and
Distance2/T= V1 + V2
1662/3= 554 = V1 - V2
2142/3= 706= V1 + V2
Now solve this 2x2 system, by substitution
then
V1= (554+ 706)/2= 1260/2= 630
V2= 706 - 630= 76
Then answer is
Velocity of plane= 630 km/h
Velocity of air= 76 km/h