if a=4 and b=(-12) what is then 2ab-b/a

\(a = 4 \\ b = -12 \\ \frac{2ab - b}{a} = \frac{2 \times 4 \times -12 - \left (-12 \right )}{4} \\ = \frac{8 \times -12 - \left (-12 \right )}{4} \\ \frac{-96 - \left ( -12 \right )}{4} \\ = \frac{-84}{4} \\ = -21\) 

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