There are systems that are obviously of second grade, such as:
$$x^2 + y = 1$$ $$y = x - 1$$
The definition of an n-th grade system is:
The grade of a system is the product of the grade of all the equations inside it.
In the above system, the grade is $2 * 1 = 2$
But let me show you another system:
$$x ^ {(4/3)} + y = 8$$ $$x ^ {(6/4)} - 2y = 1$$
I apply the definition above and get:
$$ grade = 4 / 3 * 6 / 4 = 2 $$
So the nasty looking system with fractional exponents is just a second grade system like the easy peasy one at the top? If so how can I solve it simply?
Based on your comment, your definition of an equation's grade seems to be that of polynomial degree. If so, an equation with non-integer exponents has no grade, so the latter system has no grade.