How to calculate annual depreciation and monthly depreciation when original value, salvage rate and depreciable life are known?

1. Tax-controlled computer residual value = original value * residual value rate = 2349.57 * 5% = $117.48;

2. Tax-controlled computer annual depreciation = (2349.57-117.48)/3 = $744.03

Or tax-controlled computer annual depreciation = 2349.57 * (1-5%)/3 = $744.03