12, because there are 12 inches in 1 foot.
But, to answer how many slabs, we need to find how many slabs fit 14 feet.
18 in = 1.5 ft, so we need 14/1.5=9⅓ slabs. To fill an area 18 ft (12 slabs) by 9×1.5=13.5 ft (9 slabs) we set up a 12×9 slab array. 9×12=108 slabs.
But we need to make up from 13.5 to 14 ft. That’s 6 inches to fill, which is ⅓ slab. If 4 slabs are cut into three pieces 6 inches wide, we end up with 12 pieces 6 inches wide—enough to fill the whole 18 feet and take the width up to 14 feet. That makes the total number of slabs 108+4=112 slabs.
