E$9-10($Algo$)$ Calculating Variable Overhead Variances $[$LO $9-5]$

Parker Plastic, Incorporated, manufactures plastic mats to use with rolling office chairs. Its standard cost information for last year follows:

$\backslash$table$[[,$Standard Quantity,Standard Price $($Rate$),\backslash$table$[[$Standard Unit$],[$Cost$]]],[$Direct materials $($plastic$),13$ square foot,$$1\mathrm{.}55$ per square foot,$$20\mathrm{.}15$n