(7x^12+8x^2-14x^10-16)-(7x^12-7x^10+17x^8)-(8x^2-7x^8)=7x^12+8x^2-14x^10-16-7x^12+7x^10+17x^10-17x^8-8x^2+7x^8=10x^10-10x^8-16
(2x^9-25x^3+0.8x^6-10)-(2x^9+0.8x^6-25x^3)=2x^9-25x^3+0.8x^6-10-2x^9-0.8x^6+25x^3=-10
(7x^12+8x^2-14x^10-16)-(7x^12-7x^10+17x^8)-(8x^2-7x^8)=7x^12+8x^2-14x^10-16-7x^12+7x^10+17x^10-17x^8-8x^2+7x^8=10x^10-10x^8-16
(2x^9-25x^3+0.8x^6-10)-(2x^9+0.8x^6-25x^3)=2x^9-25x^3+0.8x^6-10-2x^9-0.8x^6+25x^3=-10