Yuky purchased a new truck January $1,2012$ for $$75,000.$ The truck had an estimated life of $6$ years and a salvage value of $$15,000.$ Find the depreciation expense at December $2017$ using the following methods i$.$ sum of year digit ii$.$ double declining method. ii if the truck was sold on December $31,2017$ for $$40,000.$ what is the entry to record the gain or loss using the i$.$ sum of year digit ii$.$ double declining method