# boolean expressions simplification Help needed.

I am stuck simplifying. Can anyone help?

It states that

$$(XY’+YZ)’ = X’Y’ + X’Z’+YZ’$$

I tried all axioms yet I can't figure it out.

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Your first expression $(XY'+YZ)'$ simplifies as $(XY')'(YZ)'=(X'+Y)(Y'+Z')=(X'+Y)Y'+(X'+Y)Z'$.
Then since $YY'=0$, this is $X'Y'+0+X'Z'+YZ'=\boxed{X'Y'+X'Z'+YZ'}$ as desired.