"Limba Portugaliei și a Braziliei este portugheza."

Translation: The language of Portugal and Brazil is Portuguese.

[nahuatl1939]

and it is also the language of Cabo Verde, Guinea, Sao Tome and Principe, Angola and Mozambique. it is also still spoken in the State of GOA in INDIA. and a little in the now Chinese city of MACAO. . Altogether some 270 millions people.

[nfmonteiro]

Also an official language in Timor Lorosae and Equatorial Guinea.

[Mapka15]

It is portugheza, because it is a noun (meaning the Portuguese language). Portugheză is the adjective, so than the word "limba" has to be there too.
You can use: "limba portugheză" or just "portugheza" .

[countvlad]

Why is it not portugheză ?

[eharwagon]

The ā means that portughezā is modifying limba. Replace the ā with an a and it becomes a noun! :)

[PiotrWdkie]

Why in one exercise there is no in front of Braziliei and in this one is mandatory?

[Ursu_Brun]

I think the best comparison is in this exact sentence, "limba Portugaliei" versus "a Braziliei", and the explanation is that for "Braziliei" you don't repeat the noun "limba" therefore you substitute it with the "a".