最近，我安装了 Ubuntu 64amd，使 duak 启动与 Windows 7 32 位。一切正常，但我无法在其中安装 sagemath。即使代码正确，它也会显示“无法找到包 sagemath-upstream-binary”。我可以知道为什么吗？
这是我使用的完整代码：
sudo apt-add-repository -y ppa:aims/sagemath
sudo apt-get update
sudo apt-get install sagemath-upstream-binary
以下是终端代码：
kutubuddin@kutubuddin-h81m-s:~$ sudo apt-add-repository -y ppa:aims/sagemath
[sudo] password for kutubuddin:
Ign:1 http://ppa.launchpad.net/aims/sagemath/ubuntu bionic InRelease
Get:2 http://security.ubuntu.com/ubuntu bionic-security InRelease [69.9 kB]
Err:3 http://ppa.launchpad.net/aims/sagemath/ubuntu bionic Release
404 Not Found [IP: 91.189.xx.xx xx]
Hit:4 http://in.archive.ubuntu.com/ubuntu bionic InRelease
Hit:5 http://in.archive.ubuntu.com/ubuntu bionic-updates InRelease
Hit:6 http://in.archive.ubuntu.com/ubuntu bionic-backports InRelease
Reading package lists... Done
E: The repository 'http://ppa.launchpad.net/aims/sagemath/ubuntu bionic Release' does not have a Release file.
N: Updating from such a repository can't be done securely, and is therefore disabled by default.
N: See apt-secure(8) manpage for repository creation and user configuration details.
kutubuddin@kutubuddin-h81m-s:~$ sudo apt-get update
Ign:1 http://ppa.launchpad.net/aims/sagemath/ubuntu bionic InRelease
Get:2 http://security.ubuntu.com/ubuntu bionic-security InRelease [69.9 kB]
Hit:3 http://in.archive.ubuntu.com/ubuntu bionic InRelease
Err:4 http://ppa.launchpad.net/aims/sagemath/ubuntu bionic Release
404 Not Found [IP: 91.189.xx.xx.xx]
Get:5 http://in.archive.ubuntu.com/ubuntu bionic-updates InRelease [65.4 kB]
Hit:6 http://in.archive.ubuntu.com/ubuntu bionic-backports InRelease
Reading package lists... Done
E: The repository 'http://ppa.launchpad.net/aims/sagemath/ubuntu bionic Release' does not have a Release file.
N: Updating from such a repository can't be done securely, and is therefore disabled by default.
N: See apt-secure(8) manpage for repository creation and user configuration details.
kutubuddin@kutubuddin-h81m-s:~$ sudo apt-get install sagemath-upstream-binary
Reading package lists... Done
Building dependency tree
Reading state information... Done
E: Unable to locate package sagemath-upstream-binary