Boolean expression with only OR,NOT gates
Q: \$\overline{x}y+x\overline{y}+\overline{y}z\$, Turn this into NOT and OR gates only.



Just apply De Morgan's law on each of them individually. 

Here's a refreshener:

\$\overline{AB}=\overline{A}+\overline{B}\$

\$\overline{A+B}=\bar{A}\bar{B}\$

\$\overline{\overline{A}}=A\$



First add some not gates. 

\$\overline{\overline{\overline{x}y}}+\overline{\overline{x\overline{y}}}+\overline{\overline{\overline{y}z}}\$

Then De Morgan them to the maximum.

Here's the continuation in hidden format, I do encourage you to apply De Morgan's law on your own. 


  \$\overline{\overline{\overline{x}}+\overline{y}}+\overline{\overline{x}+\overline{\overline{y}}}+\overline{\overline{\overline{y}}+\overline{z}}\$


And after you've applied De Morgan's Law, then you might want to remove unnecessary gates. Use these two yellow boxes as a way to control that you've calculated correctly.


  \$\overline{x+\overline{y}}+\overline{\overline{x}+y}+\overline{y+\overline{z}}\$




This is how it looks like in a schematic.