85*9+150*(-2) = 85*(-1)+150*vb2
\(\large 85\times 9+150\times (-2)=85\times (-1)+150\times v_b^2\)
\(\large 150v_b^2=765-300+85\)
\(\large v_b^2=\frac{765-300+85}{150}\)
\(\Large v_b=\pm\sqrt{\frac{5}{3}}\)
\(\Large v_{b_1}=1.29099\)
\(\Large v_{b_2}=-1.29099\)
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