Suppose you did not have access to inverters.

Explain how and why you can use a NAND gate in place of an inverter gate? Make Boolean expressions for functions $1$ and $2$ that only uses NANDs.

~ The expression for $1$ must use no more than four NANDs.

~ The expression for $2$ must use no more than three NANDs.

Hint: Use $=(+)(+)$