A baseball team plays in a stadium that holds \( 74000 \) spectators. With the ticket price at \( \$ 10 \) the average attendance has been \( 30000 \) . When the price dropped to \( \$ 6 \) , the average attendance rose to \( 37000 \) . Find a demand function \( D ( q ) , \) where \( q \) is the quantity/number of the spectators. (Assume \( D ( q ) \) is linear) 

\( D ( q ) = \square \)