Erlkönig: Cute Math

Silly equation students posed to their departing math teacher:

9x - 7we > 3(3x - 7u)

Which he then solved as:

9x - 7we > 3(3x - 7u)
9x - 7we > 9x - 21u
    -7we >     -21u
     7we <   21u
      we < 3u
∴     we <3 u

Awwww....