The faces are either rectangles (4 of them, all different) or trapezia (two of them both the same, like ABCD.) I'm sure you can work out their areas. (You will need to use Pythagoras' Theorem to find AB.)
To get the volume, multiply the area of the uniform cross-section (that's ABCD) by the length (that's the distance front-to-back).
Can you complete it now?