Now, if we assume this takes place very quickly, then equilibrium is established very quickly. And if equilibrium is established, what that means is the rate of the four reaction is equal to the rate of the reverse reaction. And so we can basically determine what the rate law is of this reaction and the reverse reaction and we set them equal. So the rate law going this way is given to us by K minus one multiplied by the concentration of this should be the enzyme substrate complex. And that is equal to going this way. So K one multiplied by the concentration of the enzyme and the concentration of the substrate.