Answer
$7x^2y-4xy$ has a degree of 3.
Work Step by Step
$$(5x^2y-3xy)+(2x^2y-xy)$$ $$=5x^2y-3xy+2x^2y-xy$$ $$=5x^2y+2x^2y-3xy-xy$$ $$=(5+2)x^2y + (-3-1)xy$$ $$=7x^2y-4xy$$
This expression has a degree of 3. To find the degree of the express, use the degree of the term with the largest degree. There are two terms: 7x^2y and -4xy. The term 7x^2y has a degree of 3 because you add together the degrees of each of the variables: x has a degree of 2, y has a degree of 1. The term -4xy has a degree of 2 as both the x and y each have a degree of 1.