Exercise: the best concert ever

Question

Hello,one of the sentences to be translated was: They were even better than in my dreams.The best answer is: Eran aún mejor que en mis sueños.Why isn't it "mejores" here? "Eran aún mejores que en mis sueños."Thanks!

Accepted Answer

Hola Deborah
Here "mejor" is an adjective and it should indeed agree with the subject which is plural (they) -That will be corrected shortly. 
I tried to find a justification to that "mejor" in the singular form and I think it is because we are talking about "they" but we are thinking about "a band" as a singular subject. Also, "mejor" could sometimes be an adverb (invariable word) and this sentence is very similar to this other one using the adverb (not the adjective):

Tocaban mejor que en mis sueños.
They played better than in my dreams.

Here mejor is an adverb meaning "in a better way".
Un saludo
Inma

Answer

Mejores means "best", mejor means "better"