Can someone help explain four-bit adders and subtractors?

The following figure shows the four-bit Adder Subtractor Your inputs for this combinational circuit are A-7, B = 5 and M-1 What S the outputs S show how to get the outputs by indicating each carry bit S2 St and ? You have to A, B, A2 B2 A B Ao Bo IM The following figure shows the four-bit Adder-Subtractor. Your inputs for this combinational circuit are A 3, B 4 and M 1. What is the outputs S3, S2, S, and So? You have to show how to get the outputs by indicating each carry bit C3 C1 FA FA FA A, B, A2 B2 A B Ao Bo S3 So C1 FA FA FA FA (2 pts) The following figure shows the eight bit Adder Subtractor Your inputs for this combinational circuit are A-16, -31 and M Si, and So? You have to show how to get the outputs by indicating each carry bit. 1 What IS the outputs S, S, Ss, S Sa B, B, C3 Cs C2 C1 FAFA ST S6 Ca