Gridiron Merchandising anticipated selling 27,000 units of a major product and paying sales commissions of $6 per unit. Actual sales and sales commissions totaled 27,500 units and $171,400, respectively. If the company used a flexible budget for performance evaluations, Gridiron would report a cost variance of:

$6,400U.

$6,400F.

$9,400U.

$9,400F.

None of the other answers are correct.

show work please