ECONOMIC RENT

首先你要先知道咩野係 economic rent.
economic rent 即係收入果一 part 多過做其他野的收入.
好似我可以做老師, 我會有 hkd 20000, 我的機會成本係做工人, 收入 hkd 15000, 我的 rent 就係 hkd 5000.
由於做工人係我的 oc, 即係 higher value alternative, 我做世界上任何一份工都唔可以收多過 hkd 15000, 如果唔係果份工就會成為我的 新 oc.
即係而家我做老師會多賺 hkd 5000, 呢個就係我的 rent la!
你的題目的 total revenue 就係 hkd 2000, total cost 係 hkd 15000, 所以 difference 就係 rent la
點解 total cost 會係 hkd 15000? 因為我地要知道, 我地讀 econ 所講的係 economics cost, 唔係 accounting cost, 所以呢度的 total cost 係講我地的 opportiunity cost, 所以佢地的 difference 就係 economic rent la.

希望你明啦~

Because the difference between EXPECTD total revenue and EXPECTED total (opporunity) cost (of keeping resources in current use). is economic rent.

Any UNEXPECTED component goes to profit.

And if the total cost refers to the opportunity cost of not selling the resources, then in expected sense, difference between total revenue and total cost is zero.