If y varies directly with respect to x, then
y = k*x
Solving for k, we get
k = y/x
Pick any column of (x,y) values and plug it into the equation
I'm going to pick (x,y) = (4,10)
k = y/x
k = 10/4
k = 5/2
k = 2.5
So the equation is y = 2.5*x or simply y = 2.5x
Answer is choice F