115ft is a best case scenario they average around 70 - 90 ft.
USB wireless sticks have a short range because they have a shorter antenna than a inbuilt card, you can get USB adapters with a external antenna they are hard to find though. if you are having a hard time finding one try turning the range boost on (if your router has that feature) or get a linksys range boost pack.
Oh an it is a little hard to Imagen a USB lead in a 75ft length because after 5meaters the 5v will not reach the device that you wish to power.