than and/or

If Tom is busier than Tim & Tom is busier than Chip, then Tom is busier than Tim __ Chip.

Which word should I use to fill in the blank, and or or?

This is a tricky question.  We all know Tom is the busiest person. 

But the correct expression is: Tom is busier than Tim or Chip.  You really can't say Tom is busier than Tim and Chip...does it mean Tim and Chip combined?

Take another example.  Tom makes $100,000 a year.  Tim makes $80,000.  Chip $50,000.
Then you would say "Tom makes more money than Tim or Chip."  It is also correct to say "But Tom makes less money than what Tim and Chip make together." 

Now let's say Mary makes $130,000 a year.  Then then you can correctly say: Tom makes more money than Tim or Chip, but not (as much as) Mary.

Don't drink or drive. = Don't drink and don't drive.

Don't drink and drive. = Don't drive after you have drunk. (Drinking and driving are combined.) 

Russia is bigger than Taiwan or China. = Russia is bigger than Taiwan and Russia is bigger than China.

Russia is bigger than Taiwan and China. = Russia is bigger than Taiwan combined together with China.