$(10$ POINTS$)($Section $9\mathrm{.}4)$

For the system in the following figure, assume the neutral wire is broken as shown. The current drawn by the first house is $2$ A and that drawn by the second house is $4$ A $.$ The system has:

$R_{g-xfm}=20,R_{g1}=R_{g2}=30,R_{h1}=R_{h2}=1,R_{n1}=R_{n2}=1$

Compute the ground potential rise at noint $($Gortinn a $1$