Learn Italian: Riesci a distinguere entrambe le ragazze? - Can you manage to distinguish both girls?

In Italian, the quantifier entrambi (and its feminine form entrambe) must always be followed by a definite article when it comes before a noun. So, while English says "both girls", Italian requires the exact equivalent of "both the girls" (entrambe le ragazze).

How would I say this using the tutti e due structure instead of entrambe?

You would say tutte e due le ragazze. Just like entrambi, the expression tutti e due requires the definite article before the noun. Because ragazze is feminine, you must change tutti to the feminine plural form tutte.

Why use riesci a instead of puoi for "can you"?

While potere (where puoi comes from) means "can" in the sense of having permission or a general possibility, riuscire means "to manage to" or "to be able to" do something through effort, skill, or overcoming a difficulty. Distinguishing the two girls requires visual or mental effort, making riesci the most natural choice.

Why is there an a between riesci and distinguere?