Consider the following premises. exists x_8: R(x_8) <-> T(x_8). forall x_8: Q_1(x_8) -> R(x_8). forall x_8: T(x_8) -> Q_1(x_8). Can we infer exists x_8: R(x_8) <-> T(x_8) from them?
That is one of the premises. Therefore, the answer is yes.