Julia Rozzi had obtained a new truck with a list price, including options, of $27,000. The dealer had given her a “generous trade-in allowance” of $6,000 on her old truck that had a wholesale price of $3,200. Sales tax was $1,620.

The annual cash operating costs of the old truck were $5,250. The new truck was expected to reduce these costs by one-third, to $3,500 per year.

Compute the amount of the original investment in the new truck. Explain your reasoning.