Answer
$\frac{55}{12y}$.
Work Step by Step
In order to add or subtract fractions, we start by making a common denominator (bottom of the fraction). Thus, we multiply 9/4y by 3/3 and 7/3y by 4/4 to obtain:
$\frac{28}{12y}$+($\frac{27}{12y}$)=$\frac{55}{12y}$.