Each year’s level of production and price (per bushel) for most agricultural products affects the level of production and price for the following year. Suppose the soybean crop in a country was 80 million bushels in 2014 and
[price each year] = 20 - .1 * [quantity that year] [quantity each year] = 5 * [price from the preceding year] - 10,
where quantity is measured in units of millions of bushels.