Yo if u know Spanish, plz help me out

In which of the following sentences is the capitalized word or phrase used or placed incorrectly? a. ¿quién lo conoce á él? b. elena conoce a los dos. c. roberto conoce para maría y por alberto. d. ¿quién conoce a maría?

Choose the pronoun that would correctly replace the following subject and type it in the space provided. a guy in your class a0

Solve for x: log(x + 3) - log x = 2