Analysis: put the generation of Xiaojun's solution in to get the correct m and the wrong n, and then put the generation of Xiaohong in to get the correct n and the wrong m.

Solution: 1 substitute x=7/3 y=2/3.

mx+2y=6 2x+ny=8

The solution is m=2 and n=5.

Then substitute x=-2 y=4.

mx+2y=6 2x+ny=8

The solution is m= 1 and n=3.

So Xiaojun regarded n as 5 and Xiaohong regarded m as 1.

The correct solution is to put m=2 and n=3 in it.

mx+2y=6 2x+ny=8

X= 1，y=2。