Fill in the blanks in each of the following so as to make the statement true: (i) Two quantities are said to vary ______ with each other if they increase (decrease) together in such a way that the ratio of the corresponding values remains same. (ii) `x\ a n d\ y` are said to vary directly with each other if for some positive number `k` , _____ (iii) If `u\ =3\ v ,` then u and `v` vary ______. with each other.