I'm going to show you how to do the first question. The other questions have to be done similarly:

Let denote the speed of the air-plane through still air and the speed of the wind.

Speed of the air-plane and tail wind add up to the resulting speed; the difference between the speed of the air-plane and the head wind is the resulting speed on the return flight. Speed is defined by:

You'll get a system of simultaneous equations:

Solve for and . I've got