$X=ABC \\ Y=AB\oplus BC \\ Z=ABC + (AB\oplus BC)\\ = ABC + (\overline{AB}(BC)+AB(\overline{BC}))\\ =ABC + ((\overline{A} + \overline{B} )BC) + AB(\overline{B}+\overline{C}))\\ = ABC+\overline{A}BC+AB\overline{C}\\ = BC + AB\overline{C}\\ = B(C+\overline{C}A)\\ = B(A+C)$
