Managerial accouting

Kellar Corporation manufactured 1,500 chairs during June. The following variable overhead data pertain to June: Budgeted variable overhead cost per unit ---> $12.00 Actual variable manufacturing overhead cost ---->>$16,800 Flexible-budget amount for variable manufacturing overhead --->?$18,000 Variable manufacturing overhead efficiency variance --->$360 unfavourable What is the variable overhead flexible-budget variance