UDP and TCP use 1s complement

UDP and TCP use 1s complement for their checksums. Suppose you have the following three 8-bit bytes: 01010011, 01010100, 01 110100. What is the 1s complement of the sum of these 8-bit bytes? (Note that although UDP and TCP use 16-bit words in computing the checksum, for this problem you are being asked to consider 8-bit sums.)Show all work. Why is it that UDP takes the 1s complement of the sum; that is, why not just use the sum? with the 1s complement scheme, how does the receiver detect errors? Is it possible that a
1-bit error will go undetected? How about a 2-bit error?