Answer: x + 3.
Explanation:
The expression: [tex] \frac{x}{y} + \frac{3}{y} [/tex] is a sum of two fractions with equal denominator.
The sum of two equations with equal denominator permits copy the common denominator and add the numerators. This is the result:
[tex] \frac{x}{y} + \frac{3}{y} = \frac{x+3}{y} [/tex]
So, the numerator is x + 3.