Fix unmet dependency(ibc6-dev breaks libgcc-9-dev)

Well, this kind of unmet dependency occurs mostly when you mess around with the sources list.

now, if you’re running a stable release of distro and used the unstable sources to install somethin, please add that too. else, some other dependency may occur too.

First things first,

install  gcc-8-base  by typing  sudo apt install gcc-8-base  if already installed

install  gcc-9-base  type-in,  sudo apt install gcc-9-base

This will fix it.

at end of the installation if you see something like  couldn't configure libc6:amd64  then just reinstall  libc6

by typing,  apt reinstall libc6