4. A lumber store stocks dowels in one standard length of 150 cm. Each dowel costs $20. A customer wants the store to cut him at minimal cost twenty dowels of length 67 cm, eighty dowels of length 51 cm, sixty dowels of length 28 cm, and forty dowels of length 15 cm. You might wish to use Excel to help make a list of patterns when beginning part (a). Make a formula to be copied for all patterns which will calculate the waste. The pattern must be discarded if this calculated number is negative or if it's greater than the smallest dowel size sought by the customer (15 cm in this example).

Use excel solver or lingo to solve and produce a solution

c) explain your solution