Answer:
y = 4x
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 = 3 when y = 12
k = [tex]\frac{y}{x}[/tex] = [tex]\frac{12}{3}[/tex] = 4
y = 4x ← equation of variation
