Apply mesh current analysis in the bridge arc

$($i$)$ Find the unknown resistance $R_1,$ given that $I_1,I_2$ & $I_3$ is $1\mathrm{.}5A,0\mathrm{.}5A$&$2\mathrm{.}5A$

respecturely respecturely

$($ii$)$ Mesh $1($one$)$ KLRV equation is$?$

$($iii$)$ Mesh $2($two$)$ KLRV equalion is $?$