A circuit made up of $6$ resistors is shown in the figure, with resistances R$1=22\backslash$Omega $,$ R$2=65\backslash$Omega $,$ R$3=43\backslash$Omega $,$ R$4=51\backslash$Omega $,$ R$5=86\backslash$Omega $,$ and R$6=68\backslash$Omega $.$ The total current going through the circuit is I $=4\mathrm{.}5$ A$.$ Express the equivalent resistance of the combination of R$3,$ R$4,$ R$5$ and R$6.$