The problem states that y = 12 when x = 36. 36/12 is 3. This means that y is a third of what x is. This would mean that if x = 60, y would be a third of 60 which is 20 since 60/3 is 20.
Beneficial terms of trade or trading price between two parties are opportunity costs lower than the cost to manufacture them locally which benefits both parties. They must be less enough to cover the freight charges or additional service charges that may arise.
