Keith Whittingham, as manager of Designs by Whittingham, is upgrading his CAD software. The high-performance (HP) software rents for $3,000 per month per workstation. The standard-performance (SP) software rents for $1,600 per month per workstation. The productivity figures that he has available suggest that the HP software is faster for his kind of design. Therefore, with the HP software he will need 5 engineers and with the SP software he will need 6 . This translates into a variable cost of $200 per drawing for the HP system and $240 per drawing for the SP system. If it is projected that the volume will be 90 drawings per month, then renting software is the best option available to Keith