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 play tennis or x_10 will write a letter. For all x_10, x_10 will not play tennis or x_10 is a mechanic. If Mary were a mechanic, then Jennifer is a musician. Jennifer is a musician or Mary is not writing a letter.
If Mary writes a letter, then Jennifer is a musician can be inferred via the rewriting rule. For all x_10, x_10 will write a letter or x_10 is a mechanic can be inferred via the universal resolution rule.