Area of Rectanglar box problem!??

Question

http://i2.photobucket.com/albums/y48/xxkrystinaxx9/7_15i.gif

In the figure above, the area of the base of the rectangular box is 21 and the area of one of the faces is 30. Each of the dimensions j, k, and l is an integer greater than 1. What is the volume of the rectangular box?

Answer 1

since j and k must be (greater than 1) integer factors of 21, they must be 3 and 7
face area is either 3l or 7l and = 30, so l must be 10.
that makes volume 3(7)(10) = 210.