Now, once again, whenever our rate law is not the first step, it's the second or third step. We have to take into consideration the intermediate guys because the intermediate guys will determine the concentration of reactants for the slow step. And that's why they need to be taken into consideration. So what we basically did is first we found the rate law for our first reaction, for our fast reaction for going the forward and going backwards. And then we found the rate law for the second reaction going one way because it's the slow step. And then we basically represent the intermediate concentration as everything else.