Answer
$y=7x$
Work Step by Step
$y$ is directly proportional to $x$ so the equation that relates the variables is:
$y=kx$ where k = constant of proportionality.
If x = 6, then y = 42. Substitute these values into the equation above to have:
$y=kx
\\42 = k(6)
\\\dfrac{42}{6}=k
\\7=k$
The constant of proportionality is $7$. Thus, the equation that relates x and y is:
$y=7x$