Question

Jerry sells dishes of ice cream. Any dish has up to 3 different flavors. He decides to include an additional flavor. Is 8 the number of extra different dishes of ice cream that Jerry can sell with up to 3 flavors?

Yes For eg if the three flavours were A,B and C initially then the possible combinations would be AB,BC,AC,ABC,A,B,C and if 4th flavour was added and if that was called D then the possible combinations would be ABC,BCD,ACD,ABD,D,AD,BD,CD,AB,BC,AC,ABC,A,B,C out of which ABC,BCD,ACD,ABD,D,AD,BD,CD are new combinations if you count them it equals to 8.
I think the main thing to keep in mind here is ANY DISH HAS UP TO 3 DIFFERENT FLAVOURS.
Hope that helps!