$\mathbf{A}=2 \hat{i}+3 \hat{j}-\hat{k}, \mathbf{B}=\hat{i}+2 \hat{j}-\hat{k}, \mathbf{C}=\hat{i}+b \hat{j}+3 \hat{k}$.

$\bar{A}=2 \hat{\imath}+3 \hat{\jmath}-\widehat{k}, \bar{B}=2 \hat{\imath}+\hat{\jmath}+\widehat{k}, \bar{C}=a \hat{\imath}-7 \hat{\jmath}+10 \widehat{k}$