The provisions of this chapter regulating nonresidential uses shall be subject to such exceptions or modifications as herein provided by the following supplementary regulations.

No public or private garage for more than five motor vehicles shall have an entrance or exit for motor vehicles within 50 feet of a residential district.

Where a residential district is bounded by a portion of a business district, any side street extending through such residential district into such business district shall not be used for any business purpose, except as herein set forth. The business structure erected in said business district shall face and open upon the street set aside for business purposes, except that show windows in such business structure may be built and exposed upon said side street within the area set aside as a part of such business district, and an entrance may be made at the corner of such business and residential streets, and all other entrances thereto must face on the business street, except that entrances may be made from such residential street to the upper stories of such business structure.