In this question, it is given that y varies inversely as x . So the equation is
[tex] y = \frac{k}{x} [/tex]
And here k is the proportionality constant .
And when x=6, y=12
[tex] 12 = \frac{k}{6}
\\
k =72 [/tex]
So the values of the proportionality constant k is 72 and the correct option is B.
