Translate the following inference to logic notation: There is at least one x for which x will make tea if and only if x is a cashier. For all x, x is a taxi driver or x is a cashier. For all x, x is a taxi driver if and only if x will make tea. Therefore there is at least one x for which x will make tea.
exists x: P(x) <-> Q(x). forall x: R(x) or Q(x). forall x: R(x) <-> P(x). Therefore exists x: P(x).