Machinery acquired at a cost of $90,000 and on which there is accumulated depreciation of $50,000 (including depreciation for the current year to date) is exchanged for similar machinery. For financial reporting purposes, present entries to record the disposition of the old machinery and the acquisition of new machinery under each of the following assumptions:

Price of new, $115,000: trade-in allowance on old, $4,000: balance paid in cash
Price of new, $115,000: trade-in allowance on old: $44,000: balance paid in cash

I'll show the first entry (assumption 4,000 in trade in) in two steps however it could be done in one.

This entry removes the equipment from the ledger
DR: Accumulated depreciation 50,000
DR: Gain/Loss on disposal 40,000
CR: Equipment 90,000

This entry accounts for the new equipment in consideration of the trade in allowance
DR: Equipment 115,000
CR: Cash 111,000
CR: Gain/Loss on disposal 4,000

This should give you a good example in order to complete the second assumption.