..::''I REALLY NEED HELP WITH PLANET QUESTIONS AND THUSTS. THANKS so MUCH... BEST ANSWER 10 POINTS :) ''::....?

Thrust is acceleration isn't it? So that would be the unknown a (for acceleration). Just find the appropriate equation or set of equations. You might have to add or subtract two sets of equations together. I am good at math, but kind of a long time from my physics studies.