I think you should have to subtract the non-working from the working.
'00 Acura 1.6EL: + 4
'80 Ford F150: +8
'67 Ford LTD: +8
'56 Oldsmobile Holiday 88: +8
mercury outboard: +2
air compressor: +1
chainsaw: +1
mower: +1
grasswhip: +1
leaf blower: +1
'77 Porsche 930: -6 :cry:
35 the easy way and 29 the hard way.
