clear up vs untangle

clear up

verb
  • To clarify, to correct a misconception. 

  • To depart or disappear. 

  • To clean up. 

  • To become free of certain blemishes. 

  • Of stormy weather, to dissipate, to become calm. 

  • To pot all of the remaining balls in a single turn. 

untangle

verb
  • To remove confusion or mystery from. 

  • To remove tangles or knots from. 

How often have the words clear up and untangle occurred in a corpus of books? (source: Google Ngram Viewer )