题目里是3/z吧.
若1/x+2/y+3/z=4,3/x+2/y+1/z=6
则1/x+2/y+z/3 + 3/x+2/y+1/z
=4/x+4/y+4/z
=4(1/x+1/y+1/z)
= 4 + 6
则
1/x+1/y+1/z = 10/4 = 5/2