cals per 24.8g:
WPC (unflavored) 113
Isolate (unflavored) 105
blend (banana) 111
so,
113x + 105y = 111
(113*0.8) + (105*0.2) = 111.4
I'm assuming that the splenda/flavoring adds an insignificant amount of cals in a 24.8g serving since the blend isn't offered unflavored.
This would give an 80% WPC, 20% Isolate mix, which sounds reasonable...but could also be completely wrong.