Answer:
35 units
Step-by-step explanation:
72 units are on hand:
customer orders for periods 1, 2 and 3 = 17 + 12 + 8 = 37 units
units available for commitment to new customers = 72 - 37 = 35 units
these units can be committed either at week 1, 2, or 3.
Customer orders for period 4 will be covered with the 150 units that should arrive during period 4.