Install lib32gfortran-5-dev-x32-cross by entering the following commands in the terminal:
sudo apt update sudo apt install lib32gfortran-5-dev-x32-cross
Description:
Runtime library for GNU Fortran applications (32bit development files)
This package contains the headers and static library files needed to build GNU Fortran applications.
Homepage: http://gcc.gnu.org/
Version: 5.5.0-12ubuntu1cross1
Section: universe/libdevel