Problems with bcmath

Hi, I am testing the use of a couple of IP2 plugins including this one. I get a message saying the PHP extension needs to be enabled in the php.ini file. I checked the extension is installed but I am not sure what needs to be in the php.ini file in order to enable it. On tried a different server and there was nothing to do as it worked fine.

I am using ubuntu 20.04 and PHP 7.4 on both servers. To confirm the module is installed I check the following command:

apt-cache search php7.4 | grep php7.4

Which returns: php7.4-bcmath – Bcmath module for PHP

PHP7.4-fpm status show it is is running, but when I try the command

php7.4 -m

Then bcpmath is not listed

If I try to install the bcmath extension with

sudo apt-get install php7.4-bcmath

then I get an error

The following packages have unmet dependencies:
php7.4-bcmath : Depends: php7.4-common (= 7.4.3-4ubuntu2.15) but 1:7.4.30-3+ubuntu18.04.1+deb.sury.org+1 is to be installed

I am not sure what this means. Could you please point me in the right direction / provide the lines of code that need to be in the PHP.ini file?

Thanks