Translate the following inference to logic notation: For all x, x_11 will listen to a song if and only if x_11 will make tea. For all x, x_11 will listen to a song if and only if x_11 will make tea. Therefore if Robert listens to a song, then Robert is making tea.
forall x: P(x) <-> Q(x). forall x: P(x) <-> Q(x). Therefore P(a) -> Q(a).