DDBM: A construction company decided to purchase a concrete mixer truck for $75,000 with a trade-in of their old mixer. The old mixer has a trade-in value of $20,000. The new mixer will be kept for 10 years before being sold. Its estimated salvage value at that time is expected to be $5,000. Assume interest to be 10%. Determine the 7th year BVB by Double Declining Balance Method (round-off k to 4 decimal places).