Answer:
y = - 2x
Step-by-step explanation:
Given that x and y vary directly then the equation relating them is
y = kx ← k is the constant of variation
To find k use the condition x = - 5, y = 10, thus
k = [tex]\frac{y}{x}[/tex] = [tex]\frac{10}{-5}[/tex] = - 2, hence
y = - 2x ← is the equation relating them
