A shop sells $$\text{CD}$$s for $$\text{x}$$ pounds each.  Darren buys $$8$$ of these $$\text{CD}$$s.  What is an expression, in terms of $$\text{x}$$ for the total cost of $$8$$ $$\text{CD}$$s?  ~\uline{~~~~~~~~~~}~ 
Overseas Competition->Knowledge Point->Calculation Modules->Basic Concepts of Equation->Equivalent Substitution->Using a Letter to Represent an Unknown Number