It's the slope for compound A and the green line represents the pressure of the slope for compound B. Now, as we go as we increase the mole concentration in compound one or compound A, the pressure of it increases. And as we go this way, the mole fraction of this guy compound B decreases. So as we go this way, the vapor pressure of compound B decreases. Now, at any given time, we could find a final vapor pressure and we find the final vapor pressure by summing the two pressures. So for example, say at this point the total pressure is this guy plus this guy gives you this plus this.