Charlassier Corporation manufactures and sells laptop computers and uses standard costing. For the month of September there was no beginning inventory, there were $3,000$ units produced and $2,500$ units sold. The manufacturing variable cost per unit is RM$385$ and the variable operating cost per unit was RM$312\mathrm{.}50.$ The fixed manufacturing cost is RM$450,000$ and the fixed operating cost is RM$75,000.$ The selling price per unit is RM$925.$Required:Prepare the income statement for Charlassier Corporation for September under variable costing.$[25$ marks$]($b$)$Explain the difference between the variable and absorption costing methods.$[5$ marks$]($c$)$Explain which method costing method is suitable for external reporting or internal reporting.$[5$ marks$]($d$)$Differentiate between the adoption of $$Variable costing$$ and $$absorption costing$$ in business.$[10$ marks$]($e$)$Explain why $$job costing$$ techniques are useful in decision making.$[10$ marks$]$