EFG Ltd$.$ produces plastic chairs for kindergarten. EFG uses a standard cost system. During January $2023,$ EFG used $11,220$ plates for manufacturing, costing $$42,636.$ EFG paid direct labor costs $$157,794$ for $8,670$ hours of direct labor. The standard cost per chair assumes $1\mathrm{.}0$ plate per chair at $$4$ per plate, and $0\mathrm{.}8$ hours of direct labor per chair at $$20$ per hour. The budgeted quantity of products for January $2023$ were $10,000$ chairs, while the actual quantity was $10,200.$

a$.$ Calculate the price variance and quantity variance relating to direct materials used in the manufacture of chairs in January $2023$

b$.$ Calculate the wage rate variance and direct labor efficiency for January $2023$

c$.$ Assume that EFG specifies $7\%$ of budgets as the thresholds for variances, identify which adverse variances calculated are above the threshold and should be analyzed? Specify possible causes and recommend corrective actions for improvement?