Maths equations doubt cpt

Area of a rectangular garden is 8000 sqr mtrs . Ratio in mlength and breadth is 5:4 . A path of uniform widtth runs all around the inside of the garden. If the path occupies 3200 sqr mtrs occupies, what is its widtth? A. 12m B.6m C. 10m D. 4m please do texplain the method also... thanks