The given expression simplifies to:

$24y + 4i$

This is already in the form $a + bi$, where $a = 24y$ and $b = 4$.

Would you like any further details or explanations on this? Here are some related questions you might find interesting:

1. How do we multiply complex numbers?
2. What is the significance of the imaginary unit $i$ in complex numbers?
3. How do you convert a complex number to its polar form?
4. What is the geometric interpretation of multiplying complex numbers?
5. Can complex numbers be used to solve real-world problems?

Tip: When multiplying complex numbers, remember that $i^2 = -1$, which helps in simplifying expressions involving imaginary parts.