How many unit cubes are in the object below? If one of the layers of the cube were removed, what would the volume be? Help me plzz I'm in the middle of a quiz!

Every weekday, mr. jones bikes from his home to his job. sometimes he rides along two roads, the long route that is shown by the solid lines. other times, he takes the shortcut shown by the dashed line. how many fewer kilometers does mr. jones bike when he takes the shortcut instead of the long route?