In order to find out how many more days (d) Mars takes than Earth to orbit the sun, you'll need to subtract 365 from 687, so your equation would look like this:
687 - 365 = d
Now to solve this equation :
687 - 365 = d
322 = d
This means that Mars takes 322 days more than Earth to orbit the sun.
There you go! I really hope this helped, if there's anything just let me know! :)
