$($a$)$ Simply the Boolean function x$\text{'}$y$\text{'}$z$\text{'}+$y$+$xy$\text{'}$z$\text{'}$ to $2$ number of literals and draw a logic circuit. $($b$)$ Simply the Boolean function $($x$+$yz$)\text{'}+($x$+$y$\text{'}$z$\text{'})\text{'}$ to $1$ number of literals and draw a logic circuit. $($c$)$ Simply the Boolean function wxy$\text{'}$z$\text{'}+$wy$\text{'}+$wx$\text{'}$y$\text{'}$z$\text{'}$ to a minimum number of literals and draw a logic circuit.