Chapter 5, Problem 8P

A 2.00 kg object is subjected to three forces that give it an acceleration $\stackrel{\to }{a}=-\left(8.00 m/s^2\right)\hat{i}+\left(6.00 m/s^2\right)\hat{j}$. If two of the three forces are ${\stackrel{\to }{F}}_1=\left(30.0 N\right)\hat{i}+\left(16.0 N\right)\hat{j}$ and ${\stackrel{\to }{F}}_2=\left(12.0 N\right)\hat{i}+\left(8.00 N\right)\hat{j}$, find the third force.