Balloon Force: 2005 #22 (similar)

6 DTC 9 is one of my favorite Guidebook pages (TBG Move). It shows all the forces you will need on a single page. It was a labor of love.

So if you are asked for the force from say the ballooning effect, it's just a glance: Keep in mind the dPt and dPc are pressure changes, so find the initial and final pressures in both the casing and the tubing.

You typically chase down the BHTP using hydrostatic. For example at 10,000 ft, 8 ppg:
Initial Tubing: 0.052(8)10,000 = 4,160 psi. If surface: 0 psi, dPTa1 = 2,100 psi
Final Tubing: Surface & BHP say 6,000 & 7,900 psi you average: dPTa2  = 6,950 psi
From initial & final tubing psi, find the change by subtracting: 6,950 - 2,100 = 4,850 psi

Casing pressure change is often just given as an increase, say 1,000 psi.
Calculate or look up the tubing ID & OD area. That's easy; here we will use 7.0 & 9.6 in.
Thus: -0.6 [(4850*7) - (1000*9.6)] = -14,600 psi (up).

The units are negative (note the sign in front) which means tension.
Since pressure increased, we should indeed see tension if the packer is fixed.
These problems can be very confusing. Go slow; be sure the numbers make sense. Once you've done a few, it's fairly easy.