(a) Prime cost method

\[
\$30{,}000 \times \left(\frac{1}{5}\right)=\$6{,}000
\]

First-year deduction: **$6,000**

(b) Diminishing value method

\[
\$30{,}000 \times \left(\frac{2}{5}\right)=\$12{,}000
\]

First-year deduction: **$12,000**

Controlling authority: **Division 40 of the Income Tax Assessment Act 1997 (Cth)** (capital allowances/decline in value rules).