1)C=-A-B (using signed 1's complement)

2)D=-A+B(using signed 2's complement)

3)A-B(using 9's complement)

that is what i've tried

1)i convert A and B into binary, which are A=001100.100,B=000001.011.

-A-B=+(-A)+(-B)

1's complement of A is 110011.011, and 1's complement of B is 111110.100

and then 110011.011+111110.100=1110001.111(carry 1 ), so 110001.111+1=110010.111

2)-A+B=+(-A)+B

2's complement of A is 110100.011

so 110100.011+000001.011=110101.110

i don't know if these are correct or not, thanks for help

also how do i do the number 3, with 9's complement