Đáp án: $\widehat{a'bc'}=70^{0}$
Giải thích các bước giải:
Ta có:
+ $\widehat{abc}+\widehat{abc'}=180^{0}$ (kề bù)
$\rightarrow \widehat{abc'}=180^{0}-\widehat{abc}$
$\leftrightarrow \widehat{abc'}=180^{0}-70^{0}=110^{0}$
+ $\widehat{abc'}+\widehat{a'bc'}=180^{0}$ (kề bù)
$\rightarrow \widehat{a'bc'}=180^{0}-\widehat{abc'}$
$\leftrightarrow \widehat{a'bc'}=180^{0}-110^{0}=70^{0}$
Vậy $\widehat{a'bc'}=70^{0}$