No person shall operate a motor vehicle on any street, alley, or other place at a rate of speed greater than twenty-five (25) m.p.h. within the residential district, and twenty (20) m.p.h. within the business district, and twenty (20) m.p.h. in the school district unless a different rate of speed is specifically permitted by ordinance. In no instance shall a person drive a vehicle on a highway at a speed greater than is reasonable and prudent under the conditions. Where a different maximum speed is set by ordinance, appropriate signs shall be posted. (Ref. 60-6,185, 60-6,186, 60-6,190 RS Neb.) (Amended by Ord. No. 282, 8/6/85)