Under open trade,

$($a$)$ country $1$ will be importing and country $2$ exporting $12$ units at a price of $$10.$

$($b$)$ country $1$ will be importing and country $2$ exporting $9$ units at a price of $$11.$

$($c$)$ country $2$ will be importing and country $1$ exporting $15$ units at a price of $$11.$

$($d$)$ country $2$ will be importing and country $1$ exporting $9$ units at a price of $$14.$

$($e$)$ country $2$ will be importing and country $1$ exporting $9$ units at a price of $$11.$