Q 21 :    

Let $\alpha =8-14i,$ $A=\{z\in \mathrm{ℂ}: \frac{{\displaystyle \alpha z-\overline{\alpha }\overline{z}}}{{\displaystyle z^2-{\left(\overline{z}\right)}^2-112i}}=1\}$ and $B=\{z\in \mathrm{ℂ}:|z+3i|=4\}.$ Then $\sum _{z\in A\cap B}(Rez-Imz)$ is equal to ________.          [2023]