1 mile is equal to 5280 feet.
5/5 - 2/5 = 3/5 of a mile left to walk
3/5m * 5280 ft/1m = (3m*5280ft)/(5*1m) = 15840ft/5 = 3158 feet left to walk to get to work.
Or
5280 feet / 5 = 1056 ft * 2 = 2112 ft walked to get to work
5280 - 2112 = 3168 feet left to walk to get to work.