Answer:
C
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 that y = 10 when x = 2, thus
k = [tex]\frac{y}{x}[/tex] = [tex]\frac{10}{2}[/tex] = 5 , thus
y = 5x ← equation of variation → C