Use the following information to answer the given question.
\(\begin{array}{c|c} & & N \\ \hline \text{Purchases:} & \text{raw materials} & 20,000 \\ & \text{finished goods} & 15,200 \\ \text{Stock 1/1/89:} & \text{ raw materials} & 3,000 \\ & \text{work-in-progress} & 2,500 \\ Wages: & direct & 22,800 \\ & indirect & 7,200 \\ \text{Factory expenses:} & electricity & 12,000 \\ & insurance & 2,000 \\ \text{Stock 31/12/89:} & \text{raw materials} & 4,000 \\ & \text{work-in-progress} & 4,500\end{array}\)
The cost of materials used is