I'm glad to answer your question.

The analysis is as follows:

Suppose the plane speed is x kilometers per hour and the wind speed is y kilometers per hour.

Then 12.5(x+y)=9750.

13(x-y)=9750

therefore

x+y=780

x-y=750

amount to

2x= 1530

x=765

y=780-x= 15

So the speed of the plane is 765 kilometers per hour and the wind speed is 15 kilometers per hour.

~ I hope the answer will help you. Please continue to "ask questions" if you have any questions!

Hope to adopt it in time! thank you