RB's Plant Building (Original Cost $600,000; Estimated Useful Life, 30

RB's plant building (original cost $600,000; estimated useful life, 30 years, residual value, $120,000) no longer has space for storage of raw materials. At the start of Year 21, the company purchased an addition (a wood building) which was attached to the plant building. The wood building cost $60,000 and, under normal conditions, would have a useful life of 15 years and no residual value.
Give the entry that RB should make at the end of the accounting period, December 31, Year 21, to record amortization expense, assuming straight-line amortization for these capital assets. Clearly explain the basis for any assumptions you have made. $\begin{array} { | l | l | } \hline \text { Amortization Expense } & 22,000 \\\hline \text { Accumulated Amortization } & 22,000 \\\hline \$(600,000-\$ 120,000) / 30=&\$ 16,000 \\\hline & \\\hline \$ 60,000 / 10 = & \$ 6,000 \\\hline\end{array}$