Speedy Delivery has a very lazy accountant. When originally setting up the delivery trucks into the accounting system, the accountant did not want to calculate the expected salvage value for each vehicle. He left salvage value at $0 even though this is not the case. Explain what leaving the salvage value at $0 would do for depreciation. Discuss the differences, if any, between straight-line, double-declining, and units-of-production methods due to leaving the salvage value at $0.