Ajet can travel the 6000 km distance between washington, d. c. and london in 6 hours with the wind. the return trip against the same wind takes 7 hours 30 minutes. find the speed of the jet in still air and the rate of the wind.

 d = r*t is the basic distance equation
 d = 6000 km
 t with the tail wind = 6 hr
 r with the tail wind = speed of the plane + wind speed = s + w
 t with the head wind = 7.5 hr
 r with the head wind = speed of the plane - wind speed = s-w
 (s+w)*6 = 6000
 (s-w)*7.5 = 6000
 s + w = 1000
 s - w = 800
 2s = 1800
 s = 900 km/h
 s + w = 1000
 w = 100
 Check the anwer by calculating the return trip.
 (900-100) * 7.5 = 800 * 7.5
 800 * 7.5 = 6000 km
  The rate of the jet in still air is 900 km/h. The rate of the wind is 100 km/hr.

It's have to be 12 or idk