What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? For all y_1, if y_1 makes tea, then y_1 is playing squash. For all y_1, y_1 will play squash if and only if y_1 is happy. For all y_1, y_1 is happy.
For all y_1, if y_1 plays squash, then y_1 is happy. For all y_1, if y_1 were happy, then y_1 is playing squash.