Mikael needs to determine the direct materials usage variance. Which of the following equations should he use? a $.$ Direct materials usage variance$=($Actual price of materials$-$Standard price of materials$)$ Actual amount purchased b $.$ oirect materials usage variance$=($Actual quantity used$-$Standard quantity use $)$ Standard price $.$ oirect materials usage variance$=($Actual hours worked$-$Standard hours$)*$ Standard wage d $.$ Durect materials usage vance$=($Actual wages$-$standard wages$)*$ Actual number of direct labor hours