I need help ASAP will mark brainliest

Bob is putting books on a shelf and takes a break after filling 18 1/2 inches on the book shelf. the book shelf is now 2/3 full. how long is the entire bookshelf?

Which figures are polygons? select each correct answer. figure a figure b figure c figure d

How many revolutions will a car wheel of diameter 28 in. make over a period of half an hour if the car is traveling at 60 mi/hr? the final answer is supposedly 21,609 but i have no idea how to get that, show work : )