Answers for "unable to locate package php7.4-mbsring"

: Unable to locate package php7.4-fpm

sudo apt install software-properties-common
sudo add-apt-repository ppa:ondrej/php
sudo apt update
sudo apt install php7.4
php -v

E: Unable to locate package php7.2-mbstring

sudo add-apt-repository "deb http://archive.ubuntu.com/ubuntu $(lsb_release -sc) universe"