Question 10606
Let v be speed of plane through air and w the speed of the wind

 From A to B the plane is traveling at speed v-w with the headwind

 It takes 12 hours to go 120 miles 

 12(v-w) =120

  v-w = 10

 From B to A the plane is traveling  at speed v+w with the tail wind

 It takes 2 hours  to go 120 miles

 2(v+w) = 120

 v + w = 60

 Solve the system   v-w = 10, v + w = 60