I have tried Andrew's suggestion which was fine in that the jpeg opened in ACR. However I have always been able to open a jpeg and then just used FILTER/CAMERA RAW to achieve the same effect.
However my query was "How can I use SUPER Resolution on a JPEG/TIFF". No matter which way I open the JPEG I cannot get the ENHANCE option, it may be impossible to do so........unless someone can suggest otherwise. I am stuck on ACR 15.1.1
Thanks again