Here is the item again:
As he scrubbed the tile grout with a toothbrush and bleach. Nick vowed never
again to let the bathroom get so filthy.
You chose to use Punctuation Rule 2 to fix the problem:
Subordinate Clause + , + Main Clause.
Here is the correction:
As he scrubbed the tile grout with a toothbrush and
bleach,
Nick vowed never again to let the bathroom get so filthy.
Super job! Enjoy your cyber popcorn!