What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? Name the inference rule being used: For all x_10, x_10 will make tea if and only if x_10 is sad. For all x_10, if x_10 plays squash, then x_10 is making tea. For all x_10, if x_10 were sad, then x_10 is playing squash.
For all x_10, if x_10 were sad, then x_10 is making tea can be inferred via the universal transitivity rule. For all x_10, if x_10 makes tea, then x_10 is sad can be inferred via the universal biconditional elimination rule. For all x_10, if x_10 were sad, then x_10 is making tea can be inferred via the universal biconditional elimination rule.