已知二分之x=三分之y=四分之z
∴y=3x/2;z=2x;
3x-2y+z分之2x+y-z
=(2x+y-z)/(3x-2y+z)
=(2x+3x/2-2x)/(3x-3x+2x)
=3x/2/2x
=3/4