Learn Portuguese (Portugal): Eu estava a pôr o triplo do açúcar na balança. - I was putting triple the sugar on the scale.

In Portuguese, multipliers like o triplo (triple) or o dobro (double) function as nouns meaning "the triple amount" or "the double amount". Because of this, you need the definite article o before them, and you connect them to the next noun using the preposition de (of). Here, de combines with the article o (the) before açúcar to make do, literally meaning "the triple of the sugar".

Does the word triplo change its ending if the thing being measured is feminine?

No, because o triplo acts as a noun here, it is always masculine and singular. If you were weighing flour (a farinha, feminine) instead of sugar, you would still say o triplo da farinha, keeping triplo exactly the same.

Why use estava a pôr instead of the simple past tense pus?

Estava a pôr is the European Portuguese past continuous tense ("was putting"). It is formed with the imperfect of estar (estava) plus a and the infinitive verb. It emphasizes that the action was actively ongoing at a specific moment in the past, whereas pus ("I put") would imply a single, completed action.

Why does the verb pôr have an accent mark?