Please Help I don't understand!

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

What is the missing statement in step 4? ? rts ? ? vtu and ? rtu ? ? vts ? rts ? ? rvs and ? rtu ? ? stv ? vrs ? ? vru and ? usr ? ? usv ? vur ? ? vus and ? uvs ? ? sru

If you double the input of a function and it results in half the output, and if you triple the input and it results in a third of the output, what can be guessed about the function? check all that apply.