I need help on a math problem...does anyone know how to solve this?

[rabbitseatcarrot]

Okay here's the problem:

You are planning a rectangular garden. Its length is twice its width. You want a walkway 2 ft. wide around the garden.
A) Write an expression for the ares of the garden and walk.
B) Write an expression for the area of the walk only.
C) You have enough gravel to cover 76 ft. squared and want to use it all on the walk. How big should you make the garden?

If someone could please explain to me how to solve this problem. Thank you!