A baseball team plays in a stadium that holds 46000 spectators. With the ticket price at $9 the average attendance has been 20000. When the price dropped to $5, the average attendance rose to 23000. Find the demand function $D(q)$, where $q$ is the quantity/number of the spectators. (Assume $D(q)$ is linear)
$D(q) = $
(For best results, keep answers in fraction form, not decimals)