<span><span>Rene Descartes is known
for the Cartesian coordinate system and the belief that mathematics can explain
all of nature. He is the father of analytical geometry (by using algebra
to describe geometry). We often relate to his Cartesian coordinate system in
maps or graphs to know how far along and how far up it is. </span>He
was also the one who invented the representation of unknowns in
mathematical equations by using x, y, and z, and then the
knowns by using a, b, and c<span>.</span></span>
D, I don't remember the others, but as I recall, white man tried to keep the blacks enslaved, and tenant farming was the next best thing<span />
The best option regarding US trade policy in the 1930s would be that the US sought to "<span>Increase the price of farm products and industrial goods by increasing the taxes on imports," since this was during the Great Depression. </span>
Probably around 600 miles