Need to know how to work b and c

The following costs are associated with three tomato- peeling machines being considered for use in a canning plant. If the canning company uses an inter- est rate of 12%, which is the best alternative? Use NPW to make your decision. (Note: Consider the least common multiple as the study period.) Machine First cost O&M costs Annual benefit Salvage value Uxclullile dyrs $52.000 15.000 38.000 13.000 4 $63.000 9.000 31.000 19.000 $67.000 12.000 37.000) 22.00%) 12