Luxury destinations for To produce 400 units of corn, including all the necessities of workers, we need 260 units of corn and 14 units of iron. Similarly, to produce 20 units of iron, we need 140 units of corn and 6 units of iron. Then, operations for a production period (say a year) would be written as follows: 260 corn + 14 iron 400 corn 140 corn + 6 iron 20 iron 400 corn 20 iron In this system, since 14 units of iron must exchange for 140 units of corn, the exchange (or price) ratio between them must be one unit of iron for 10 units of corn for this economy to be able to function. No other price ratios would work. Production with surplus. Next, Sraffa examines a similar economy with a surplus. Here the same quantities of input yield output of 570 units of corn and 20 units of iron. Luxury destinations 2016.