Identify Each Cost Below as Variable (V), Fixed (F), or Mixed

Identify each cost below as variable (V), fixed (F), or mixed (M), relative to units sold. Explain the reason for your answer.
$$\begin{array} { | l | r | r | r | } \hline \text { Units Produced } & 100 & 500 & 1,000 \\\hline \text { Total electric cost } & \$ 1,500 & \$ 1,650 & \$ 1,700 \\\hline \text { Supervisor's monthly salary } & \$ 4,500 & \$ 4,500 & \$ 4,500 \\\hline \text { Assembly line workers' per hour wage rate } & \$ 30 & \$ 30 & \$ 30 \\\hline \text { Total materials cost } & \$ 800 & \$ 4,000 & \$ 8,000 \\\hline \text { Depreciation on factory equipment } & \$ 5,000 & \$ 5,000 & \$ 5,000 \\\hline \text { Total delivery costs } & \$ 1,400 & \$ 1,800 & \$ 2,250 \\\hline\end{array}$$