If the value of “y” varies directly with “x” and y = -8 when x = 20, find “y” if x = -4.

Answer:
y = [tex]\frac{8}{5}[/tex]
Step-by-step explanation:
Given 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 = - 8 when x = 20
k = [tex]\frac{y}{x}[/tex] = [tex]\frac{-8}{20}[/tex] = - [tex]\frac{2}{5}[/tex]
y = - [tex]\frac{2}{5}[/tex] x ← equation of variation
When x = - 4, then
y = - [tex]\frac{2}{5}[/tex] × - 4 = [tex]\frac{8}{5}[/tex]