`Answer:`
\(\widehat{xOy}+\widehat{xOt}=180^o\) (Hai góc kề bù)
\(\Rightarrow80^o+\widehat{xOt}=180^o\)
\(\Rightarrow\widehat{xOt}=100^o\)
Ta thấy:
\(\widehat{xOy}=\widehat{zOt}=80^o\) (Đối đỉnh)
\(\widehat{xOt}=\widehat{yOz}=100^o\) (Đối đỉnh)
Vậy \(\widehat{zOt}=80^o\)