Now suppose, for example, if I added more x, if I add more x, I would change my concentration of x. And that means for a few seconds or for some time, my concentration of x would change and this would shift equilibrium this way, causing x to be converted to Y at a faster rate than y converted to x. And that's called leisurely air principle and we'll talk about that in another lecture. So now let's suppose we have the following elementary reaction in which our reactants x and y convert to our product z and W. Now, A-B-C and D are the coefficients that represent the moles of each respective atom. Now let's suppose our reaction is a dynamic equilibrium. And what that basically means once again is that the rates at which x and Y are converting to z and W is the same as the rate at which z and w is converting to x and Y.