X varies directly with y where x =5, y=15 find the relationship with x and y

When $x$ varies directly with $y$, the relationship can be written as:

$$x = ky$$

where $k$ is the constant of proportionality.

Given $x = 5$ and $y = 15$:

$$5 = k(15)$$

Divide both sides by 15 to solve for $k$:

$$k = \frac{5}{15}$$ $$k = \frac{1}{3}$$

Substitute the value of $k$ back into the direct variation formula:

$$x = \frac{1}{3}y$$

The relationship between $x$ and $y$ is $\boxed{x = \frac{1}{3}y}$.