And that's because the concentration of the enzyme is usually much, much smaller than the concentration of the substrate. For instance, we can have a million of the substrate molecules, but only 100 of the enzyme molecules. And so what that means is we can no longer make the assumption that this is much smaller than this. And so in this particular case, we actually have to leave the equation as it is. Now we want to use equation seven to basically replace this quantity in terms of the total amount of enzyme and the enzyme substrate concentration. And so what we want to do is we want to use equation seven and solve for this quantity here.