"The black pants."
Translation:Na brístí dubha.
Should the singular translation be counted as a correct answer? "the black pants" (the prompt) could refer to singular or plural numbers of pants, I think. My singular answer was not marked wrong, but counted as "typos", but I feel that it the English sentence is ambiguous and wanted to see if I could construct the singular Irish equivalent correctly. In Irish, would it be correct to translate that prompt both to "Na bristi dubha" and to "An briste dubh"?
For what in English would refer to one pair of trousers the singular "bríste" should be used. Incidentally, the English word 'trousers' is derived form the Irish 'truis', while the Irish 'bríste' comes from the English breeches'! (Pants originated in Italy, but that is a long story)
You don't say which lessons Tips & Notes you read it in, but I'm assuming that you are referring to this entry from the Colours lesson:
An adjective that follows a plural noun has its spelling changed to the plural form of that adjective. If the noun ends with a slender consonant, the adjective is also lenited.
Brístí doesn't end with a slender consonant, it ends with a slender vowel.
In Irish, an adjective (including colours) that is an attribute of a noun agrees with the case (nominative or genitive), the number (singular or plural) or the gender (masculine or feminine) of the noun.