(1). An engineer wants to complete a building in 60 days by employing 60 workers. Upon reviewing the work after 45 days, he notices that only one-third of the work is complete. In order to completely built the building in 60 days, how many extra worker must he employ now?

• (a). 180
• (b). 240
• (c). 300
• (d). 420
• (e). None of these