Установите Bcmath Php 7.3 Ubuntu
sudo apt-add-repository ppa:ondrej/php
sudo apt update
sudo apt install -y php7.3 php7.3-cli php7.3-common
BlessedDog
sudo apt-add-repository ppa:ondrej/php
sudo apt update
sudo apt install -y php7.3 php7.3-cli php7.3-common