Final answer:
The equation representing the relationship between x and y is y = 5x.
Step-by-step explanation:
The relationship between x and y can be represented by the equation y = kx, where k is the constant of proportionality. To find the value of k, we can use the given information that when x = 3, y = 15. Plugging these values into the equation, we have 15 = k * 3. Solving for k, we find k = 5. Therefore, the equation representing the relationship between x and y is y = 5x.
Learn more about Linear Proportions