A welcome feature in current Mac OS (El Capitan, Sierra) is that by default Word documents sent to you are opened in Pages. You don't need to concern yourself at all with Word when you are on the receiving end of work.
When you send out your document to someone who wants to see it in Word export it via
File > Export To > Word...
When the dialogue window opens you have an option of either converting the Pages document to .docx format or to an older version of Word. Click on Advanced options tab and choose a previous version of Word to have a .doc format file.