GNU/Linux Mint 19 Installing Broadcom BCM4331 Driver Guide
Hi! The linked Tutorial shows you Step-by-Step How to Install Broadcom BCM4331 Wi-fi/Bluetooth Driver in Mint 19.x Tara/Tessa/Tina/Tricia LTS GNU/Linux.
The Package Provides the Source Code for the wl Kernel Modules and makes use of the DKMS Build Utility to Install them for the Running Kernel.
GNU/Linux Mint 19 Broadcom BCM4331 Driver Installation Guide