50 is not a perfect square because it does not have a perfect square root where as 49 is 7, 121 is 11, and 1 is 1
5km = 5000 meters
450m+800m= 1250m
5000m-1250m= 3,750m
3 3/4 km
7,200 = (24)(20)h
15=h (just divide)
To check, 20*24*15 = 7,200 cubic centimeters so 15 cm is right
I hope it isn't too late! Here is what I have.
1B
2D
3A