if p+q+r=16, b+c=4 and x,y,z are the solution of linear equations

(x/p)+(y/p-b)+(z/p-c)=1

(x/q)+(y/q-b)+(z/q-c)=1

(x/r)+(y/r-b)+(z/r-c)=1 then x+y+z is