To be sure of 2 light chocolates, 9 would need to be chosen as you would first need to eliminate the 7 dark chocolates and then pick the extra 2 light ones. For the 2 dark, 11 would bee needed as, again, the 9 lights would need to be eliminated and the other 2 dark accounted for.
So the complete amount of fishes were 100% 70% died and 60 are left... so 100% - 70% = 60 100% - 70% = 30% 30% = 60 fishes... so 10% = 20 fishes If you complete that percentage to 100 10% = 20, 100% 200
