Question 42958
We will simplify the fractions as much as we can, and then set them to the least common multiple of both denominators, so we can add them. In this case, the least common multiple of {{{axy}}} and {{{x^2y}}} is {{{ax^2y}}} Watch:

{{{cartoon(5y/axy^2 + 4b/bx^2y,
5highlight(y)/(ax*highlight(y^2)) + 4b/bx^2y,
5/axy + 4b/bx^2y,
5/axy + 4cross(b)/cross(b)x^2y,
5/axy + 4/x^2y,
5/(a*highlight(x)*y) + 4/highlight(x^2)y,
5x/ax^2y + 4/x^2y,
5x/(highlight(a)*x^2y) + 4/x^2y,
5x/ax^2y + 4a/ax^2y,
(5x + 4a)/ax^2y
)}}}

The answer is probably {{{(5x + 4a)/ax^2y}}}.