libboost

[Gordon]

Hi Folks

Could someome please tell what is meant by the following

Code Select Expand



E: Package 'libboost-filesystem1.67.0' has no installation candidate
E: Package 'libboost-program-options1.67.0' has no installation candidate
E: Package 'libboost-system1.67.0' has no installation candidate


All of the above files are already installed on my pc, so I have no idea what I am trying to sort out