Translate each in the form y = kx, where k is constant.


___________1. The distance (d) in kilometers travelled by a car varies directly as speed (s) in kilometer per hour.
___________2. The cost (c) of a dozen eggs varies directly as the price (p) of one.
___________3. The monthly expense (E) varies directly as the square of its sales (s).
___________4. The area of a rectangle (A) varies directly as its width (w).
___________5. The amount of VAT (V) varies directly as the number of items purchased (i).