systems of linear equations

Question

Flying against the wind, an airplane travels 2640 kilometers in 3 hours. Flying with the wind, the same plane travels 7800 kilometers in 6 hours. What is the rate of the plane in still air and what is the rate of the wind?

Rate of the plane in still air: km/h

Rate of the wind: km/h

Answer 1

p + w = 2640/3 = 880

p-w = 7800/6 = 1300

add them to get

2p = 2180

p = 1090 km'h for the plane with no wind

w =210 km = wind speed