The Tee Box is a golf shop inside the clubhouse ofa North Carolina golf course. Derek Dunlop, owner of the Tee Box, is deciding how much shelf space to devote to each of four different golf ball types. Derek has a maximum front shelf space of15 feet to devote to golf balls. He wants a minimum of three feet and a maximum of seven feet of front shelfspace for each golf ball type. Appropriate per-case data on the four ball types follow: Distance Spin Straight Durable Sales price per case $24.20 $22.90 $23.60 $21.10 Variable costs per case 15.80 16.20 16.80 15.10 Cases sold per foot of front shelf space per day 32 26 25 38 The daily contribution per foot of front shelf space for Straight is