Se the change of variables s=xy, t=xy^2 to compute \iint_r xy^2\,da, where r is the region bounded by xy=3,\ xy=7,\ xy^2=3,\ xy^2=7.

I think the best similarities of the two of them is that both writers wrote about things and events that are going on in their country and the comparison of them is that American writer wrote about war, racism and slavery, and politics in a current time while European writer are all about religions. I hope this would help 

Does the problem say y=x+4?