Now, once again, we're making an assumption that this is elementary reaction. So that means we can write the rate law for each reaction going this way and going that way by simply using the coefficient ADC and d.
So let's do exactly that. So the rate of our four reaction is equal to the constant for going this way. K one times the concentration of A to the A power times the concentration of y to the b power, the coefficients. And this equals the rate of the reverse reaction, the backwards reaction z and w converting back to x and y. And this equals k minus one, which is a different constant than this constant.