1. a. (5 points) Create a 3-bit adder/subtractor circuit using only Full Adders (FA) and XOR gates. Do not include a circuit for overflow calculation. Draw the circuit. b. (4 points Extra Credit) If the XOR gate has a delay of 0.6 ns, the sum bit, of the FA, has a delay of 2.4 ns and the Carry out bit, of the FA, has a delay of 2.6 ns, after how much time will the overall sum bits and the overall carryout bit, of the 3-bit adder/subtractor, will be valid?