8× 10-4(25-8)= 12 points.

So the answer is:12;

(2) If Xiaohua answers question X correctly, he answers question (25-x) incorrectly.

10x-4(25-x)= 180，

Solution: x = 20.

So the answer is: 20;

(3) Suppose Xiao Ming answers at least Y questions correctly in this competition.

10y-4(25-y)> 1 10，

Solution: x > 15.

The smallest positive integer solution of ∴x is x = 16.

A: Xiao Ming answered at least 16 correctly.