The demand function for a certain product, q = D(p), is linear, where p is the price per item in dollars and q is the quantity demanded. If p increases by $5, market research shows that q drops by two items. In addition, 100 items are purchased if the price is $550.
(a) Find a formula for
(i) q as a linear function of p
(ii) p as a linear function of q
(b) Draw a graph with q on the horizontal axis.