So I actually thought many times about the answer now and I got a question myself.
The answer under me seems mathmatic right, but it still wondered why the wind would hinder the plane in a ration of 12/18. ( As its 12minutes faster to the target ,and 18minutes late to get back to it)
If I wouldnt think about the speed of the plane in d/h, but in time I could create the following equations:
W = a negative number which shows how many minutes the winds let u reach ur destination faster
A = the time the Plane needs to reach its destination. always the same as stated in the topic
So with A being always the same + having the advantage of the wind it takes u 60mintues.
A+W = 60minutes
Now with A and the disadvantage its 90 minutes.
A-W = 90minutes
Means if i solve this equations:
A+w =60minutes
A-w =90minutes
2w = -30minutes II /2
w = -15minutes
putting this in the first equation
so A-15minutes = 60minutes
shows that A is 75minutes.
In the answer under me though its showed that A is 72minutes, when solved with involving the destination.
Im really confused here maybe someone can help