(15/8)^x*(16/9)^y*(27/10)^z=16
(3^x*5^x/2^3x)*(2^4y/3^2y)*(3^3z/2^z*5^z)=16
2^(4y-3x-z)*3^(x+3z-2y)*5^(x-z)=2^4*3^0*5^0
所以4y-3x-z=4
x+3z-2y=0
x-z=0
所以x=1,y=2,z=1
(7x+y)/(z-y)
=9/(-1)
=-9