Cannot install gcc-multilib and g++-multilib on Ubuntu 20.10 Desktop for Raspberry Pi!

[xuanvuong1702]

Describe the bug

I tried the installation but Ubuntu said that it could not find any package 'g++-multilib'.

E:Package 'gcci-multilib' has no installation candidate

E: Unable to locate package g++multilib

E: Couldn't find any package by regex 'g++multilib'

To Reproduce
Steps to reproduce the behavior:

1. install ubuntu 20.10 on Raspberry Pi 4
2. install sudo apt install --no-install-recommends gcc gcc-multilib g++-multilib
3. See error

[nordicjm]

The instructions are for ubuntu x86_64 i.e. on a PC, not a raspberry pi.