16. On one plot of 14 hectares, unsorted potatoes were planted, and on another plot of 4 hectares, sorted potatoes were planted. The average yield per hectare on these two plots is 20 centners higher than the average yield of the first plot. By how many centners is the yield of sorted potatoes higher than the yield of unsorted potatoes?
16. Let the average yield of non-variety potatoes be $x$ centners per hectare, and that of variety potatoes be $-y$ centners per hectare. Then the average yield of the two plots is $(x+20)$ centners per hectare. We have

$$
(x+20) \cdot 18=x \cdot 14+y \cdot 4
$$

from which $4 y-4 x=360 ; y-x=90$, which means that the yield of variety potatoes is higher than that of non-variety potatoes by 90 centners.