(a) In determining the power of certain home-rule municipalities to levy taxes, the taxes levied by a county, a political subdivision of a county, or a district under Article III, Section 52, of the Texas Constitution are not considered.
(b) This section prevails over a provision of a municipal charter to the extent of a conflict.

(c) This section applies only to a municipality that attempted to amend its charter before June 30, 1939, and at the time of the election to amend the charter did not own a water system, sanitary sewer system, electric light system, or natural gas system from which it could derive revenue.