Naurfold regularly buys new delivery vans. Each van costs 30,000, has running costs of 3,000 and a scrap value of 10,000 in its 1st year. In its 2nd year the van has higher running costs (4,000) & a lower scrap value (7,000). Vehicles are not kept for > 2 years for reliability reasons. Required Using Naurfold's cost of capital of 15%, identify how often the van should be replaced. Ignore tax.