The number of feet between two objects varies directly as the number of miles. if the distance between two objects is 2 and one half miles or 13,200 feet, how many feet are equivalent to a distance of 7 miles

i think the answer is b.

step-by-step explanation:

not 100% sure though.

geometry: triangles

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call the larger triangle abc

then the smaller triangle cde is similar to abc (all angles are equal, aaa).  

ab is the side that is 36, and we wish to find de, the side corresponding to ab

area_cde = area_abc - area_cde --> area_abc / area_cde = 2

let x=length of de

ratio of areas = (ratio of sides)^2

+2+=+%2836%2fx%29%5e2+

+2+=+1296%2fx%5e2+

++x%5e2+=+1296%2f2+=+648+

25.45584