Question on: WAEC Accounting - 1994

Use the following to answer the given question
(\begin{array}{c|c} & N & & N \ \hline \text{Opening stock} & 1,200 & sales & 29,000 \ Purchases & ? & \text{Less sales returns } & 500 \ \text{Add. Carriage Inwards} & 300 & & ? \ \text{Less return outwards} & 1,570 \ & 28,500 \ \text{Less closing stock} & 2,220 & \ \text{Gross Profit(25% of sales)} & 28,500 & & 28,500 \end{array})
The cost of goods available for sale is