a) $\widehat{xOy}+\widehat{yOx'}= 180^o$ ( vì 2 góc kề bù)
$→ \widehat{yOx'}=180^o-xOy$
$→ \widehat{yOx'}=180^o-130^o=50^o$
b) Vì $\widehat{Ot}$ là tia phân giác $\widehat{xOy}$ nên ta có:
$\widehat{tOy}=\widehat{tOx}=\dfrac{\widehat{xOy}}{2} =\dfrac{130}{2}=65^o$
c) $\widehat{tOx'}=\widehat{tOy}+\widehat{yOx'}=65^o+50^o=115^o$