a$)$ How can you transform the circuitry in Q$1($b$)$ to convert it into a carry$-$lookahead adder? Draw

the complete carry$-$lookahead circuit $($in terms of inputs and carries$).(20)$

b$)$ How can you use the five$-$bit carry$-$lookahead adder in $\text{'}a\text{'}$ as a block to create a twenty$-$bit

adder? Draw the circuit. No need to draw the complete lookahead circuitry. $(5)$