Lets say you have a pastel and a bumblebee. Let's say P for pastel and S for spider.

Pastel = Ppss
Spider = ppSs
Bumblebee = PpSs

So you would set it up as Ppss x PpSs
And you would get

25% PP 50% Pp 25% pp
50% Ss 50% ss

Combine the two and you would have

12.5% PPSs super pastel spider (killerbee)
12.5% PPss super pastel
25% PpSs pastel spider (bee)
25% Ppss pastel
12.5% ppSs spider
12.5% ppss normal