A) 1 foot = 12 inches. If the vine grows a half of a foot per day, then in inches that would be half of 12 which is 6 inches.
B) A day is equivalent to 24 hours. If the vine grows 0.5 feet under a period of 24 hours then, the vine can grow 0.25 inches per hour. I got this answer by dividing 6 by 24 (6 is the dividend and 24 is the divisor).