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~ # apt -t stretch-backports install libreoffice libreoffice-core libreoffice-common libreoffice-calc libreoffice-draw libreoffice-impress libreoffice-writer
Reading package lists... Done
Building dependency tree       
Reading state information... Done
libreoffice-common is already the newest version (1:5.2.7-1+deb9u11).
libreoffice-common set to manually installed.
Some packages could not be installed. This may mean that you have
requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming.
The following information may help to resolve the situation:

The following packages have unmet dependencies:
 libreoffice-calc : Breaks: libreoffice-common (< 1:5.4.1) but 1:5.2.7-1+deb9u11 is to be installed
 libreoffice-common : Breaks: libreoffice-core (>= 1:5.3~) but 1:6.1.5-3+deb10u4~bpo9+1 is to be installed
 libreoffice-core : Depends: libreoffice-common (> 1:6.1.5) but 1:5.2.7-1+deb9u11 is to be installed
                    Breaks: libreoffice-common (< 1:5.4.1) but 1:5.2.7-1+deb9u11 is to be installed
 libreoffice-draw : Breaks: libreoffice-common (< 1:5.4.1) but 1:5.2.7-1+deb9u11 is to be installed
 libreoffice-impress : Breaks: libreoffice-common (< 1:5.4.1) but 1:5.2.7-1+deb9u11 is to be installed
 libreoffice-writer : Breaks: libreoffice-common (< 1:5.4.1) but 1:5.2.7-1+deb9u11 is to be installed
E: Unable to correct problems, you have held broken packages.