Answer:
y = [tex]\frac{x}{8}[/tex]
Step-by-step explanation:
since y varies directly as x, then the equation relating them is
y = kx ← k is the constant of variation
to find k use the given condition y = 9 when x = 72
k = [tex]\frac{9}{x}[/tex] = [tex]\frac{9}{72}[/tex] = [tex]\frac{1}{8}[/tex], hence
y = [tex]\frac{1}{8}[/tex] × x = [tex]\frac{x}{8}[/tex]
