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. Remember, the two constants going this way and this way are different times the concentration of z to the c coefficient or exponent times the concentration of w to the d power. Now this guy is equal to this guy because we're a dynamic equilibrium. And the only reason we are able to write the rate laws like this using the coefficients is because this is an elementary reaction.