Ta có \(\widehat{xOy}+\widehat{x'Oy}=180^0\) (kề bù)
\(\Rightarrow5\widehat{x'Oy}+\widehat{x'Oy}=180^0\\ \Rightarrow6\widehat{x'Oy}=180^0\\ \Rightarrow\widehat{x'Oy}=30^0\\ \Rightarrow\widehat{xOy}=150^0\)
Vậy \(\widehat{x'Oy'}=\widehat{xOy}=150^0\) (đối đỉnh)
Chọn A