Elm uses the high-low method of estimating costs. Elm had total costs of $289,000 at its lowest level of activity, when 8,700 units were sold. When, at its highest level of activity, sales equaled 15,200 units, total costs were $399,500. Elm would estimate variable cost per unit as: Multiple Choice $33.22 $26.28 O $17.00 O $28.81