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Solve two math problems in senior three ~ thank you ~
Take three times, a * * * has 3*3*3=27 ways to take it.

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-