Because one might have other minerals in it as well
I would take the advancement of the refrigeration as a crucial part in the increasing of the production.
The refrigeration has been extremely important in the agriculture and the amount of production in it, because with it the agricultural products can be kept fresh for much longer periods. Because the products can be kept fresh for much longer time, that means that they can be delivered to pretty much every part of the world and not be spoiled. So the refrigeration opened up the doors for the farmers in the sense that instead producing only for the region or the country they live in, they can now produce much more for exporting, as the products will not spoil and remain fresh. That has also brought in much bigger profit for the farmers, and the production is constantly increasing because the whole market in the world is open with this technological advancement.
By rename do you mean turn into an improper fraction?
if so, it is because without turning it into an improper fraction, you cannot subtract 3/4 from 1/4 because you would get a negative answer and that would be incorrect
