Let "u" be the plane speed in still air; "v" be the speed of the wind.
Then from the condition, effective rate with the wind is
u + v = = 1010 km/h
Effective rate against the wind is
u -v = = 510 km/h
Add the two equations (1) and (2) to get
2u = 1520;
u = 1520/2 = 760.
Then from equation (1),
v = 1010 - 760 = 250.
ANSWER. The plane speed in the still air is 760 km/h. The wind speed is 250 km/h.