The rubber end comes off the tank.
Then you can do a couple of things.
Hit wrecking yard for replacement line, the whole line(s).
Make an adapter out of larger size vacuum hose or hoses, a hose that fits on the tank nipple then down size to one that the smaller hard line can fit snugly into, or use glue to seal hard line into larger hose.
These pre-made ends are made by heating the hard line and then sliding it over the nipple built into the rubber end.
You can some times heat the rubber end and remove the broken piece then heat the line and slide it on, but it is a 50/50 chance of working, because heat range is tight, line can collapse or rubber section can melt.