$(50$ points$)$ For the circuit below:

a$.(25$ points$)$ Using nodal analysis find the voltages at nodes A and $B($suggestion: use equivalent resistances$)$ and fill the table below.

$\backslash$table$[[$Variable$,$Value,Units,Points$],[$VA$,,$V$,12\mathrm{.}5],[$VB$,,$V$,12\mathrm{.}5]]$

b$.(25$ points$)$ From the values obtained in a$,$ find the following:

$\backslash$table$[[$Variable$,$Value,Units,Points$],[$VR$1,,V,8\mathrm{.}3],[$VR$5,,$V$,8\mathrm{.}3],[I_{R3},,$mA$,8\mathrm{.}4]]$