What is z minus 67 In a expression

Can someone me with my hwplz(only the circled ones)

Consider the reaction 2x2y2+z2⇌2x2y2z which has a rate law of rate= k[x2y2][z2] select a possible mechanism for the reaction.

The police chief wants to know if the city’s african americans feel that the police are doing a good job. identify the management problem (i. e dependent variable) and identify the independent variable.