```
wget -qO - https://download.sublimetext.com/sublimehq-pub.gpg | sudo apt-key add -
```

This command downloads the public key used to verify the signature of the package. After downloading the key, you can add the Sublime Text repository to your system by running the following command:

```
echo "deb https://download.sublimetext.com/ apt/stable/" | sudo tee /etc/apt/sources.list.d/sublime-text.list
```

After adding the repository, you can update the package list and install Sublime Text 3 using the following commands:

```
sudo apt-get update
sudo apt-get install sublime-text
```

I hope this helps!