A linen shop sells sheets and pillow cases .Linen from easiest company offer a choice in each set of sheets and pillow cassia plain sheet a sheet with polkadots, a sheet with stripes, a plain pillow cases or pillow cases with polkadots and stripes. customer may mix and match the plain, polkadots or strippped sheets and pillow cases in any combination. to help the shop make next order which is make a record of .how many different combination are possible?