\(\begin{array}{c|c} \text{Quantity of singlets} & \text{Short run total costs(N)} \\ 0 & 1,000 \\ 10

\(\begin{array}{c|c}

\text{Quantity of singlets} & \text{Short run total costs(N)} \\

0 & 1,000 \\

10 & 1,200 \\

20 & 1,400 \\

30 & 1,600 \\

40 & 1,800 \\

\end{array}\)

The short run total costs for different levels of output for a firm producing singlets are shown above. Calculate the variable cost per unit at an output of 20.