Final answer:
The question refers to a range of cleaning instructions (21-180) that likely discuss various household chemicals, from soap to personal care products, which might apply to maintaining the cleanliness of a bus.
Step-by-step explanation:
The cleaning instructions which involve the same parts of the bus are numbered 21 through 180. This range suggests looking at a specific section in a reference that likely discusses cleaning agents and techniques. Specifically, 21 refers to Household Chemicals, with subsections detailing various cleaning products such as soap, synthetic detergents, laundry auxiliaries like softeners and bleaches, all-purpose and special purpose cleaning products, as well as solvents, paints, waxes, and personal care chemicals. In the context of a bus, these cleaning instructions might be related to the processes or products used to maintain the cleanliness of the vehicle's interior and exterior.
The cleaning instructions listed as (21-180) refer to the different sections of a document or manual that provides instructions for cleaning various parts of a bus using household chemicals. These sections include cleaning with soap (21.1), synthetic detergents (21.2), laundry auxiliaries- softeners and bleaches (21.3), all-purpose and special purpose cleaning products (21.4), solvents, paints, and waxes (21.5), and cosmetics - personal care chemicals (21.6).