The variables x and y vary directly. Use the values to find the constant of proportionality, k. Then write an equation that relates x and y. Write any fractions in simplest form.y=45; x=40

We are given that:
variables x and y vary directly, this means that:
y = kx where k is the constant of proportionality

Now, we are also given that:
y = 45 at x = 40.
We will use these values and substitute in the above relation to get k as follows:
y = kx
45 = 40k
k = 45/40 = 9/8 = 1.125

Based on the above calculations, the equation that relates x and y is:
y = 1.125x