Work arround for circular calculation. Calculate value within a calculated range

Hello guys,

I didn't know how to describe it in the subject. Basically the idea is to have this:

200

300

calc_val

500

=1000

I want calc_val to be Total-200 so the value will always make the total = 200

Numbers will change monthly and have adjustments, so I'm looking for a formula to make the permanent calculation, but given is part of the sum to get the total, it's circular and I'm trying to find a way without using VBA.

Any ideas?