Borunda Air uses two measures of activity, flights and passengers, in the cost formulas in its budgets and performance reports. The cost formula for plane operating costs is $46,300 per month plus $2.736 per flight plus $11 per passenger. The company expected its activity in July to be 83 fights and 255 passengers, but the actual activity was 89 flights and 249 passengers. The actual cost for plane operating costs in July was S269,950. The activity variance for plane operating costs in July would be closest to: $6,243 F $16,350 F O $6,243 U $16,350 U