(208-64)÷2= 144÷2=72 points

The score of Xiaohua: 72+64= 138.

Suppose Xiaohua did the X question correctly.

20x- 12X( 10-x)= 138

32x- 120= 138

32x=258

X=8 questions

Assuming Xiaodong did the Y problem correctly,

20y- 12X( 10-y)=72

32y- 120=72

32y= 192

Y=6 questions