$6\mathrm{.}1\mathrm{.}43.[$Level $3]$ Find ${}_{\frac{?}{\text{b}\text{a}\text{r}}(BCD)}$ and $v_C$ for the given system:

${}_{\frac{?}{\text{b}\text{a}\text{r}}(DE)}=-7$kra$\frac{d}{s},r_{\frac{B}{A}}=-0\mathrm{.}6jft,r_{\frac{D}{E}}=(-i+j)ft,$

$r_{\frac{C}{B}}=0\mathrm{.}8$ift, and $r_{\frac{D}{B}}=(0\mathrm{.}8i-1\mathrm{.}2j)ft.$