(For questions 3, 4 and 5) On January 1, 20X4, Guard Security Service purchased an alarm monitoring system for $80,000. The system is expected to be used for 4 years, after which it can be sold for $16,000. 3. What is the book value of the equipment on December 31, 20X5, if Guard uses the straight-line method of depreciation? 4. If Guard uses the double-declining-balance method of depreciation, what is depreciation expense for 20X5? 5. If Guard sells the equipment for $20,000 at the end of the 4 years, the journal entry to record the sale will be