maybe I don't understand the question ...

let's say there are 80 total dwellings

according to the ratio 5:3 , there are 50 private homes and 30 apartments

of the 50 private homes, 5 are wood structures and 45 are brick

now the question asksdo houses include apartments or is the question referring to private homes only?what is the maximum portion of houses that may be brick.

also, portion of what? the total number of dwellings?

given the above numbers, 75/80 = 15/16 of the dwellings are brick, which is where the "typo" is ... imho.