What is the difference of polynomials (8r6s3-9r5s4+3r4s5) - (2r4s-5r6-4r5s4)

If you would like to solve (8r^6s^3 - 9r^5s^4 + 3r^4s^5) - (2r^4s^5 - 5r^3s^6 - 4r^5s^4), you can do this using the following steps:

(8r^6s^3 - 9r^5s^4 + 3r^4s^5) - (2r^4s^5 - 5r^3s^6 - 4r^5s^4) = 8r^6s^3 - 9r^5s^4 + 3r^4s^5 - 2r^4s^5 + 5r^3s^6 + 4r^5s^4 = 8r^6s^3 - 5r^5s^4 + r^4s^5 + 5r^3s^6

The correct result would be 8r^6s^3 - 5r^5s^4 + r^4s^5 + 5r^3s^6.