Answer:The answer to your question is: log₇ ([tex]\frac{xy}{z}[/tex])Step-by-step explanation: log₇ x + log₇ y - log₇ zFirst he must use the product rule that says: log a x + log a y = log a xyThen, he must use the quotient rule that says log a x - log a y = log a ([tex]\frac{x}{y}[/tex]He did not use these rules that's why his answer is incorrect.The correct answer is: log₇ (xy) - log₇ z log₇ [tex]\frac{xy}{z}[/tex]