Please answer all of the following questions and show your work as I will be using this to study and learn. Thank you very much in advance.

Cardinal uses the high-low method of estimating costs. Cardinal had total costs of $30,180 at its lowest level of activity, when 10,500 units were sold. When, at its highest level of activity, sales equaled 16,700 units, total costs were $39,790. Cardinal would estimate variable cost per unit as $1.55 O $2.38 O $2.87 O $2.57