y = - 3
Since y varies directly as x then
y = kx ← ( k is the constant of variation )
to find k use y = - 1 when x = 3
k = [tex]\frac{y}{x}[/tex] = [tex]\frac{-1}{3}[/tex] = - [tex]\frac{1}{3}[/tex]
hence y = - [tex]\frac{1}{3}[/tex] x
when x = 9, then
y = - [tex]\frac{1}{3}[/tex] × 9 = - 3
