At the beginning of the year, X Company expected to produce 3,100 units of its only product. Its estimate of fixed overhead was $11,000, and its estimate of variable overhead per unit was $6.60. At the end of the year, 2,500 units were actually produced, with actual total overhead cost of $30,786. What was X Company's total overhead flexible budget variance for the year [a positive number means a favorable variance; a negative number means an unfavorable variance]? \begin{tabular}{c} \hline F: \\ $5,358 \\ \hline \end{tabular}