Please help and explain #8 and #9. Thanks.

Because A-B-A+ (-B), the subtraction of signed numbers can be accomplished by adding the complement. Subtract each of the following pairs of 5-bit binary numbers by adding the complement of the subtrahend to the minuend. Indicate when an overflow occurs. Assume that negative number are represented in 1's complement. Then repeat using 2's complement. (a) 1110 (b) fi (c)-01010 (d) 9 10101 9- Construct a table for 4-3-2-1 weighted code and write 8147 using this code