Solution: If Xiaoming answers X correctly, he answers wrong (10-X), Xiaohua answers Y correctly, he answers wrong (10-Y), Xiaohong answers Z correctly, and he answers wrong (10-Z).

10X-3( 10-X)=74

13X= 104

X=8

10Y-3( 10-Y)=22

13Y=52

Y=4

10Z-3( 10-Z)=87

13Z= 1 17

Z=9

8+4+9=2 1 (orbit)

A: The three of them answered the question 2 1 correctly.