convert .docx file to regular .doc file

Hello, We have a .docx file that won't open with regular microsoft word, it needs: Office Open XML word processer so in the comments, please say if you have this software or not. The job is to open it in the office open xml word processer, and convert the file (Save as) a regular .doc file to be edited in regular word, you need to check this too before sending back needs to be done immediately in 5 minutes the file is attached Budget is $2