To answer the question above, distribute the negative sign to the subtrahend and combine like terms.
8r6s3 - 9r5s4 + 3r4s5 - 2r4s5 + 5r3s6 + 4r5s4
Combining like terms
8r6s3 + (-9r5s4 + 4r5s4) + (3r4s5 - 2r4s5) + 5r3s6
Simplifying the expressions will give an answer of,
8r6s3 - 5r5s4 + r4s5 + 5r3s6