De Morgans Theorem states that any logical binary expression remains unchanged if all variables are changed to their complements, all AND operators are changed to ORs and vice versa and complement the entire expression.
b) Express completely De Morgans Theorem using diagrams of logic gates with two inputs A and B' 
In this system a bit is reserved at the left of the most significant digit to represent sign. For example
The 1's complement representation in binary of a positive integer is similar to the sign-magnitude representation of that integer. Hence 1's complement representation of (103)10 is (01100111)2 and (97)10 will be (01100001)2
Twos complement is favoured over ones complement over a means of binary, negative number manipulation in computers because twos complement method does not require that the addition and subtraction circuitry examine the signs of the operands to determine and hence enable easy handling of higher precision arithmetic.