Schwerin Corporation Reports the Following on Its 2005 Financial Statements

Schwerin Corporation reports the following on its 2005 financial statements.
$$\begin{array} { | l | c | c | } \hline & \underline { \mathbf { 2 0 0 4 } } & \underline { \mathbf { 2 0 0 5 } } \\\hline \text { Gross P, P \& E } & \mathbf { \$ 5 0 0 \mathrm { M } } & \$ 550 \mathrm { M } \\\hline \text { Accumulated depreciation } & \$ 400 \mathrm { M } & \$ 380 \mathrm { M } \\\hline \text { Net P, P \& E } & \$ 300 \mathrm { M } & \$ 270 \mathrm { M } \\\hline \text { From statement of cash flows: } & & \\\hline \text { Cash proceeds from sale of equipment } & & \$ 100 \mathrm { M } \\\hline \text { Cash outflow for purchase of equipment } & & \$ 170 \mathrm { M } \\\hline \text { Depreciation } & & \$ 50 \mathrm { M } \\\hline \text { Gain from sale of equipment } && \$ 40 \mathrm { M } \\\hline\end{array}$$
-The net book value of equipment sold was:

A) $120M
B) $100M
C) $ 80M
D) $ 60M