▁the ▁old ▁car ▁for ▁an ▁amount ▁equal ▁to ▁the ▁mon et ary ▁disc ount , ▁and ▁the ▁deal er ▁is ▁also ▁making ▁a ▁" supp ly " ▁for ▁the ▁full ▁price , ▁providing ▁the ▁new ▁car ▁for ▁its ▁full ▁sale ▁price . ▁ ▁Car ▁deal ers hips ▁are ▁one ▁business ▁sector ▁where ▁part ▁exchange ▁de als ▁are ▁common . ▁ ▁They ▁are ▁less ▁common ▁in ▁other ▁se ctors . ▁ ▁In ▁the ▁housing ▁sector , ▁for ▁example , ▁only ▁a ▁few ▁business es ▁will ▁make ▁part ▁exchange ▁de als . ▁ ▁One ▁such ▁is ▁Bar r att ▁Hom es , ▁where ▁the ▁part ▁exchange ▁deal , ▁with ▁buy ers ▁being ▁offered ▁disc ount s ▁for ▁part ▁exchange ▁of ▁their ▁old ▁houses , ▁has ▁in ▁fact ▁been ▁an ▁integral ▁part ▁of ▁the ▁company ' s ▁business ▁model . ▁ ▁There ▁is ▁another ▁account ing ▁nic ety ▁for ▁the ▁house ▁builder ▁in ▁such ▁de als , ▁rel ating ▁to ▁when , ▁exactly , ▁to ▁take ▁the ▁profit ▁on ▁the ▁deal . ▁ ▁House ▁prices ▁change ▁over ▁time , ▁and ▁it ▁is ▁possible ▁that ▁the ▁house builder ▁may ▁not ▁be ▁able ▁to ▁eventually ▁sell ▁the ▁old , ▁ex changed , ▁property ▁for ▁the ▁same ▁or ▁more ▁than ▁the ▁value ▁that ▁it ▁was ▁originally ▁ex changed ▁for . ▁ ▁There ▁are ▁two ▁extreme ▁views ▁on ▁how ▁to ▁render ▁accounts ▁for ▁such ▁de als , ▁and ▁most ▁account ing ▁practices ▁fall ▁somewhere ▁in ▁the ▁spectrum ▁in ▁between . ▁ ▁The ▁one ▁extreme ▁has ▁the ▁profit ▁on ▁the ▁deal