So once again, the rate or average rate of x is negative change in concentration of x over time. Now, time is also multiplied by A. Now, for the case that A-B-C and D are one, we simply take away the A, because one times T is T. So the same thing can be said for w for Y. The negative change in concentration of y over BT gives you the rate of disappearance of Y. Now, the rate of appearance of W and Z can be given by these formulas where now we have the positive because these guys appear and so these guys will both be positives. Now, let's look at the factors affecting our reaction rates.