Drawing this on a paper, will give you 5280 west, then 2460 north and then straight back to the start.This will give you a triangle. The way to answer this is to first compute the total square footage of the area in problem, then divide by 43,560 which is the square footage in an acre.
So putting this mathematically: 5280 x 2460 = 12988800 (total sq footage in the box) / 2 (cut it in half to get the square footage of the triangle)
= 6494400 (total square footage of triangle) /43560 (square footage in an acre
= 160 acres.