Skizone Company's $4-$Variance Analysis: Spending Variance Efficiency Variance Production$-$Volume Variance Variable overhead $$7,100$ F $$12,000$ U No variance Fixed overhead $($a$)$ No variance $$47,000$ U If Skizone's combined $4-$Variance Analysis shows an unfavorable spending variance of $$2,400,$ what is the fixed overhead spending variance $($a$)?$