The following information were reported for Golding Inc. for period ended May $2023$ and the least square method was used for analysis.

$1$

$($activity level$)$

$2$

$($Difference from average$)$

$3$

$($Cost$)$

$4($Difference from average$)$

$5$

$($Column $22)$

$6($Column $2$x$4)$

$340$

$-24\mathrm{.}00$

$2260$

$-17\mathrm{.}20$

$576\mathrm{.}00$

$412\mathrm{.}80$

$300$

$-64\mathrm{.}00$

$2160$

$-117\mathrm{.}20$

$4,096\mathrm{.}00$

$7500\mathrm{.}80$

$400$

$36\mathrm{.}00$

$2300$

$22\mathrm{.}80$

$1,296\mathrm{.}00$

$820\mathrm{.}80$

$420$

$56\mathrm{.}00$

$2400$

$122\mathrm{.}80$

$3,136\mathrm{.}00$

$6876\mathrm{.}80$

$360$

$-4\mathrm{.}00$

$2266$

$-11\mathrm{.}20$

$16\mathrm{.}00$

$44\mathrm{.}80$

Required: Calculate the variable cost per unit for the period