Answer:
We are already given the length of the prism, so now we need to find the height and width.
4 units across is the width, and 2 units up is the height
In order to find the volume of a rectangular prism we must multiply the length, width, and height.
In this case, 4 is our width, 2 is our height, and 7 is obviously our length.
Now let's multiply;
4 x 2 x 7 = 56 cubic centimeters
to make this easier to multiply we could also do
(4 x 2) x 7 or 4 x (2 x 7)