Starting with center of thrust to find amount of force on each point?

[Tontow]

I'm playing a game, From the Depths, that let's you build your own helicopter blades (and put them on ships that you build) and program in LUA.

I did some searching and found: Calculating the Center of Thrust on Multirotors | Flite Test

Currently, there is no way to tell how much lift a given helicopter blade has.
What is known is:
- how heavy the ship is
-the location of the center of mass
- the location and direction of each helicopter blade.What I'm having trouble doing is starting out with the center of thrust and finding out how much thrust each blade needs to have out of a possible -100% to +100% power.IE: (to take from the link above)
How would you solve:
8.33 = (a*0 + s*10 + d*15) / (a+s+d)
Solve for a and s and d when power is at 50% of the maximum possible power.

Bonus: Use something that includes V/A-tail thrust

 

[Tontow]

I really don't know how I would go about solving this aside from just using guess and check.

Any help on finding a method would be appreciated.