Where the maximum value is not 3 (only 1 or No.2 ball) and 2*2*2=8 kinds.

Subtraction gives 27-8= 19.

Count, No.3 ball taking method of 65438 +0 times +2 times +3 times =

C(3， 1)*C(2， 1)*C(2， 1)+C(3，2)*C(2， 1)+C(3，3)= 12+6+ 1= 19

That's right. I am also a senior three. It's not easy, dear!

I hope to adopt-