performance management, please provide comments as well

Cumulmbus Ltd operates a standard costing system. The standard direct materials to produce 600 units of output is as follows Alatonal Cicada Input quantity (litres) Standard price per litre(E) 200 1.10 300 0.55 120 1.20 1 180 1.50 During December 2021 the actual output of the product was 10,500 units. The actual Materials issued to production were: Material Grade Quantity (litres) E 2.000 F 5,000 G 2.000 H 3,000 You are required to: a. Calculate the material mix and yield variance for each material and in total. Comment on the figures calculated. b. Explain briefly, with examples, your understanding of the following terms: 1. Planning Variance ii. Goal Congruence ili. Sub-Optimality