ATPL perf and loading question

[Turning base]

Hi everyone,
Looking for some help from the brains trust. In the event of a question that has a scenario where the aircraft CoG is out of limits and requires you to work out the minimum ballast required at a particular station to be within limits, how do you work this out if it’s not a multiple choice question? Is there a formula ?
Cheers
TB

[Fill-level]

I use many moons ago :

X=W x D
----
d

x = weight to be moved
W= total weight of helicopter
D = distance the C of G is out
d = distance between old and new locations of load moved

[Chang739]

Yep, spot on. See attached.

Also, if you wanted to dust off your Whiz-Wheel, you can use that too