Answer:
y = - 3
Step-by-step explanation:
Given that y varies directly with x then the equation relating them is
y = kx ← k is the constant of variation
To find k use the condition y = - 1 when x = 3
k = [tex]\frac{y}{x}[/tex] = [tex]\frac{-1}{3}[/tex] = - [tex]\frac{1}{3}[/tex]
y = - [tex]\frac{1}{3}[/tex] x ← equation of variation
When x = 9, then
y = - [tex]\frac{1}{3}[/tex] × 9 = - 3
