Answer
$P=\dfrac{T}{15}$
Work Step by Step
$P$ is directly proportional to $T$ so the equation that relates the variables is:
$P=kT$ where k = constant of proportionality.
If T=300, then P=20. Substitute these values into the equation above to have:
$P=kT
\\20= k(300)
\\\dfrac{20}{300}=k
\\\dfrac{1}{15}=k$
The constant of proportionality is $\dfrac{1}{15}$. Thus, the equation that relates x and y is:
$P=\frac{1}{15} \cdot T$
