Question 4: Design of Parallel Subtraction Block Diagram [30 Marks] a) Using 2s complement method subtract four bit binary number A (A3A2A1A0) from four bit binary number B (B3B2B1B0) and show the parallel block diagram of the logic circuit (i.e. B-A). b) On the block diagram show the subtraction of B(0001) and A(1010) and binary numbers. If the outcome is negative, you need to expand the block diagram so that it finds the correct answer.