$ sudo apt-get update
$ sudo apt-get install libgfortran3-mips64-cross 

libgfortran3-mips64-cross is installed in your system.

Make ensure the libgfortran3-mips64-cross package were installed using the commands given below,

$ sudo dpkg-query -l | grep libgfortran3-mips64-cross *

You will get with libgfortran3-mips64-cross package name, version, architecture and description in a table

libgfortran3-mips64-cross package basic information: