Boleeian algebra f(X,Y,Z)=(X’Y+XZ)(X+Y’)

f(X,Y,Z)=(X’Y+XZ)(X+Y’)
first evaluate
(X'Y)(X +Y') = 0 since XX'Y + X'YY' are each 0, the anded terms XX' and YY' are always 0
next evaluate
XZ(X +Y') = XXZ +XY'Z = XZ(1 +Y') = XZ since XX is just X, and 1 ored with Y' is just 1

so f(X,Y,Z)=(X’Y+XZ)(X+Y’) = XZ