Prism has 4 side faces, a top and bottom, making 6 faces altogether: 2lw+2lh+2wh=96, where the top and bottom faces are each lw, two side faces built on w are each wh and the remaining two are built on l, each lh. lw+lh+wh=48.
If you are looking for values of l, w and h that are whole numbers, we have interchangeable values: (1,6,6), (2,2,11), (4,4,4) given by the formula l=(48-hw)/(h+w). For example, (1,6,6) means (h,l,w) can be (1,6,6), (6,1,6) or (6,6,1).