1/x(x+4)+1/(x+4)(x+8)+1/(x+8)(x+12)=x-3/x(x+12) 4/x(x+4)+4/(x+4)(x+8)+4/(x+8)(x+12)=4(x-3)/x(x+12) 1/x-1/(x+4)+1/(x+4)-1/(x+8)+1/(x+8)-1/(x+12)=4(x-3)/x(x+12)1/x-1/(x+12)=4(x-3)/x(x+12)x+12-x=4x-12x=6...