Ta có: \(\widehat{MON}+\widehat{NOP}=99^o;4\widehat{MON}=7\widehat{NOP}\)
\(\Rightarrow\frac{\widehat{MON}}{7}=\frac{\widehat{NOP}}{4}\)
Áp dụng tính chất dãy tỉ số bằng nhau:
\(\frac{\widehat{MON}}{7}=\frac{\widehat{NOP}}{4}=\frac{\widehat{MON}+\widehat{NOP}}{7+4}=\frac{99}{11}=9\)
\(\Rightarrow\hept{\begin{cases}\frac{\widehat{MON}}{7}=9\\\frac{\widehat{NOP}}{4}=9\end{cases}}\Rightarrow\hept{\begin{cases}\widehat{MON}=9.7=63^o\\\widehat{NOP}=9.4=36^o\end{cases}}\)