如果x=3y,z=x/2,那么(x-y+z)/(x+y+z)=多少?

Question

如果x=3y,z=x/2,那么(x-y+z)/(x+y+z)=多少?

Answer 1

x=3y
y=x/3

(x-y+z)/(x+y+z)
=(x-x/3+x/2)/(x+x/3+x/2)
=(x-2x/6+3x/6)/(x+2x/6+3x/6)
=x(6/6-2/6+3/6)/x(6/6+2/6+3/6)
=x/x*(7/6)/(11/6)
=7/11