Introduction to thermodynamics question

[yecko]

Homework Statement

In the image, as the first chapter of thermodynamics class, I understand all things in the answer except the highlighted part (lower bottom of the image). It is not directly related to thermodynamics but about the area ratio of the two ends of the tube, but I do not understand why is the equation formed this way.
Δh (which is a decrease) should be only there in the right tube as indicated, why is it a sum of Δh of both left and right? why Δh(Hg,left)=Δh(Br) and Δh(Hg,right)=Δh(Br)*A2/A1 as well?
Thank you very much for any help!

(http://i.imgur.com/1Pjks2P.png )

2. Homework Equations
(In the image)

The Attempt at a Solution

(In the image)

 

[Chestermiller]

Your question isn't clear. The differential heights of both the mercury and the brine columns increase. You can see that from where the dotted lines are in the figure. (Incidentally, there is a typo in the 2nd of Eqns. 1. The first equal sign should be a + sign.