解:由题可得:x/2=y/3=z/4,化简得:6x=4y=3z,
由此可得x=1/2z, y=3/4z,
所以,(x+y-z)/(x+y+z)=(1/4z)/(9/4z)=1/9
由题可知:x=2t,y=3t,z=4t t不等于0;
所以:x+y+z=9t ; x+y-z=t ;
x+y+z分之x+y-z=1/9
t等于零时,无解(舍掉)
设K,2分之x=3分之y=4分之z等于k,则x=2k,y=3k,z=4k,代入x+y+z分之x+y-z等于九分之一
Z=2分之X呢?????????????