The variable x varies directly as y and x = 80 when y = 160, What is y when x is 64.

Which of the following vary directly and which vary inversely with each other and which are neither of the two?

(i) The quantity of rice and its cost.

(ii) The height of a tree and the number of years.

(iii) Increase in cost and number of shirts that can be purchased if the budget remains the same.

(iv) Area of land and its cost.

(v) Sales Tax and the amount of the bill.

If x varies inversely as y and x = 20 when y = 600, find y when x = 400.

l varies directly as m and l is equal to 5, when , find l when .

If x varies inversely as y and y = 60 when x = 1.5, find x when y = 4.5.