hi,
you can determine it by seeing if y/x = a constant value, in other words if y = (a constant value) x
then you say that y varies directly with x, and you can see that : call the constant k
then y/x is supposed to be k in all values
6/3 = 2
24/12 =2
96/48 = 2
384/192 = 2
it worked the ratio between x and y is constant so y varies directly with x ( y = 2x) and that constant k =2
p.s. you can also say that x varies directly with y but in that case it becomes x/y =constant and that constant say c is 1/2 (x = (1/2)y))
hope u understand.
Source- https://answers.yahoo.com/question/index?qid=20110813112602AApHZtQ
